Cambridge International AS & A Level
CHEMISTRY
9701/12
Paper 1 Multiple Choice
February/March 2021
1 hour
You must answer on the multiple choice answer sheet.
*9283990023*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data Booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 03_9701_12/3RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
The table shows the numbers of protons, neutrons and electrons in four different particles, W, X,
Y, and Z.
number of
protons
number of
neutrons
number of
electrons
W
32
40
32
X
32
40
34
Y
32
42
32
Z
34
40
34
Which pair represents the atoms of two isotopes of the same element?
A
2
3
W and Y
B
W and Z
C
X and Y
D
X and Z
Where in the Periodic Table is the element that has an outer electron shell arrangement of
4s24p3?
Group
Period
A
13
3
B
13
4
C
15
3
D
15
4
Substance Q is a hydrocarbon. When 1.00 g of Q is completely burned, 3.22 g of carbon dioxide
is produced.
What could be the identity of Q?
A
cyclohexene
B
cyclopentane
C
ethene
D
pentane
© UCLES 2021
9701/12/F/M/21
3
4
Originally, chemists thought indium oxide had the formula InO. By experiment they showed that
4.8 g of indium combined with 1.0 g of oxygen to produce 5.8 g of indium oxide. The Ar of oxygen
was known to be 16.
Which value for the Ar of indium is calculated using these data?
A
5
6
38
B
77
C
115
D
154
In which substance are the only intermolecular forces temporary dipole-induced dipole
attractions?
A
hydrogen chloride
B
methanol
C
octane
D
water
A solution contains 0.25 g of sulfur dioxide in 1.00 dm3 of water.
Which volume of sulfur dioxide, measured at 50 C and a pressure of 1  105 Pa, must be added
to 1.00 dm3 of water to produce this solution?
A
7
0.0162 cm3
B
0.105 cm3
C
16.2 cm3
D
105 cm3
An experiment was performed to determine the enthalpy of combustion of ethanol.
thermometer
test-tube
water
spirit burner
ethanol
The data collected are shown.
mass of water = W g
mass of ethanol burned = X g
temperature rise = Y C
molar mass of ethanol = Z g mol–1
specific heat capacity of water = 4.2 J K–1 g–1
Which expression can be used to calculate the enthalpy of combustion of ethanol in kJ mol–1?
A
4.2WYZ
1000 X
© UCLES 2021
B
4.2WYX
1000Z
C
4.2 XYZ
1000W
9701/12/F/M/21
D
4.2 X (Y  273)Z
1000W
[Turn over
4
8
VO2Cl reacts with NaI under acidic conditions.
2VO2Cl + 2H2SO4 + 2NaI  VOCl 2 + VOSO4 + I2 + Na2SO4 + 2H2O
The oxidation state of Cl is –1 in VO2Cl and in VOCl 2.
Which row about this reaction is correct?
9
vanadium
iodine
A
is oxidised
is oxidised
B
is oxidised
is reduced
C
is reduced
is oxidised
D
is reduced
is reduced
In which reaction is water behaving as a Brønsted–Lowry base?
A
H2O + Na  NaOH +
B
H2O + H3PO4  H3O+ + H2PO4–
C
H2O + CaO  Ca(OH)2
D
NH3 + [Cu(H2O)6]2+  NH4+ + [Cu(H2O)5(OH)]+
1
2
H2
10 A large excess of marble chips is reacted with 25 cm3 of 1.0 mol dm–3 hydrochloric acid at 40 C.
How is the result different when the reaction is repeated with 60 cm3 of 0.5 mol dm–3 hydrochloric
acid at 40 C?
A
The reaction is faster and more of the products are made when the reaction is complete.
B
The reaction is faster and less of the products are made when the reaction is complete.
C
The reaction is slower and more of the products are made when the reaction is complete.
D
The reaction is slower and less of the products are made when the reaction is complete.
© UCLES 2021
9701/12/F/M/21
5
11 The Boltzmann distribution curve for a gaseous mixture of ethene and hydrogen is shown. Nickel
is an effective catalyst for the reaction that occurs.
number of
particles with
energy, E
Ea (catalysed)
Ea
0
0
energy, E
How does the diagram appear if the same reaction mixture is at a higher temperature?
A
The curve is unchanged.
B
The values of both Ea (catalysed) and Ea decrease.
C
The values of both Ea (catalysed) and Ea increase.
D
The values of both Ea (catalysed) and Ea remain the same.
12 Which observations are made when a sample of silicon chloride, SiCl 4, is added to a beaker of
water?
A
No visible change is observed.
B
Steamy fumes and a precipitate are both observed.
C
The appearance of a precipitate is the only observation.
D
The appearance of steamy fumes is the only observation.
13 Which row is correct?
statement
reason
A
The first ionisation energy of phosphorus
is greater than that of magnesium.
electron is lost from a
3p orbital in both cases
B
The melting point of phosphorus
is greater than that of magnesium.
phosphorus has more valence
electrons than magnesium
C
The atomic radius of phosphorus
is smaller than that of magnesium.
phosphorus has greater nuclear
charge than magnesium
D
The electrical conductivity of phosphorus
is smaller than that of magnesium.
bonding changes from ionic in
magnesium to covalent in phosphorus
© UCLES 2021
9701/12/F/M/21
[Turn over
6
14 Which row correctly describes one property of barium and one property of barium oxide?
observation when
barium metal is
added to water
pH of solution obtained when
a spatula measure of BaO is
added to 100 cm3 of water
A
a few gas bubbles
form on the metal surface
8
B
a few gas bubbles
form on the metal surface
13
C
rapid effervescence is seen
8
D
rapid effervescence is seen
13
15 An anhydrous white salt, Z, is heated strongly for 30 minutes. A mixture of gases is given off. The
solid remaining in the test-tube is then dissolved in a small volume of dilute hydrochloric acid. The
addition of a few drops of dilute sulfuric acid to the test-tube causes a white precipitate to form.
Which substance could be Z?
A
barium carbonate
B
barium nitrate
C
magnesium carbonate
D
magnesium nitrate
16 Chlorine gas is reacted with aqueous sodium hydroxide. The oxidation number of chlorine
changes from 0 to –1 and also from 0 to +1.
Under which conditions does this reaction occur and what is the colour of the solid silver salt with
chlorine in the oxidation state –1?
reaction conditions
colour of silver salt
A
cold, dilute alkali
white
B
cold, dilute alkali
yellow
C
hot, concentrated alkali
white
D
hot, concentrated alkali
yellow
© UCLES 2021
9701/12/F/M/21
7
17 When concentrated sulfuric acid reacts with sodium iodide the products include sulfur, iodine,
hydrogen sulfide and sulfur dioxide.
Which statement is correct?
A
Hydrogen sulfide is the product of a reduction reaction.
B
Iodide ions are stronger oxidising agents than sulfate ions.
C
Sulfur atoms from the sulfuric acid are both oxidised and reduced.
D
Sulfur atoms from the sulfuric acid are oxidised to make sulfur dioxide.
18 NO, NO2, CO and unburnt hydrocarbons are present in the exhaust gases of internal combustion
engines. When catalytic converters are used to remove these compounds from the exhaust
gases, redox reactions occur.
What happens to each compound in the catalytic converter?
NO
NO2
CO
unburnt
hydrocarbons
A
oxidised
oxidised
reduced
oxidised
B
oxidised
oxidised
oxidised
oxidised
C
reduced
reduced
oxidised
oxidised
D
reduced
reduced
reduced
reduced
19 Methylamine, CH3NH2, has similar chemical properties to ammonia, NH3. Methylamine reacts
with hydrogen chloride to form a white crystalline salt, methylammonium chloride.
CH3NH2 + HCl  CH3NH3+Cl –
A sample of methylammonium chloride is heated with aqueous sodium hydroxide.
What are the products?
A
ammonia, sodium chloride and water
B
ammonia, sodium hydrogencarbonate and sodium chloride
C
methylamine, hydrogen chloride and water
D
methylamine, sodium chloride and water
© UCLES 2021
9701/12/F/M/21
[Turn over
8
20 The structures of citric acid and isocitric acid are shown.
citric acid
isocitric acid
CH2CO2H
CH2CO2H
C(OH)CO2H
CHCO2H
CH2CO2H
CH(OH)CO2H
How many chiral centres does each acid possess?
citric acid
isocitric acid
A
1
1
B
1
2
C
0
1
D
0
2
21 How many tertiary alcohols have the molecular formula C6H14O?
A
1
B
2
C
3
D
4
22 The diagram shows the structure of a bromo compound that may be formed by the reaction of
bromine with a hydrocarbon.
CH2Br
H 3C
C
CH3
CH2Br
Which row is correct?
type of reaction
mechanism
A
addition
electrophilic
B
addition
nucleophilic
C
substitution
nucleophilic
D
substitution
free-radical
© UCLES 2021
9701/12/F/M/21
9
23 Part of the structure of strobilurin is shown. R and R' are inert groups.
strobilurin
O
OCH3
R'
R
Strobilurin is warmed with aqueous sulfuric acid producing compound X. Compound X is then
treated with hydrogen in the presence of a nickel catalyst producing compound Y.
What could be the structure of compound Y?
A
B
O
HO
OH
OCH3
R'
R'
R
R
C
D
O
OH
OH
OH
OH
R'
R'
R
R
OH
24 Which compound produces
potassium dichromate(VI)?
A
pentan-1-ol
B
2-methylbutan-1-ol
C
2-methylbutan-2-ol
D
3-methylbutan-2-ol
© UCLES 2021
a
ketone
when
9701/12/F/M/21
refluxed
with
an
acidified
solution
of
[Turn over
10
25 Dibromopentanes can undergo ‘double elimination’ reactions to produce hydrocarbons.
2NaOH + C5H10Br2  C5H8 + 2NaBr + 2H2O
Which isomer produces only one hydrocarbon product?
A
1,5-dibromopentane
B
1,4-dibromopentane
C
2,3-dibromopentane
D
2,4-dibromopentane
26 The diagram shows the formation of compound Y from compound X in a chemical reaction. R1
and R2 are alkyl groups.
Y
R1
KCN
X + HCN
C
R2
Which row about this reaction is correct?
mechanism
compound X
A
electrophilic addition
aldehyde
B
electrophilic addition
ketone
C
nucleophilic addition
ketone
D
nucleophilic addition
aldehyde
© UCLES 2021
9701/12/F/M/21
OH
CN
11
27 In this question you can assume that 1H and 3H have the same chemical properties.
A sample of ethanal contains only one isotope of hydrogen, 1H.
It is reduced to compound Z, C2H6O, in a nucleophilic addition reaction using NaBH4. All the
hydrogen atoms in the NaBH4 are the 3H isotope.
CH3CHO
NaBH4
C2H6O
compound Z
Compound Z is then oxidised back to ethanal and water.
C2H6O + [O]  CH3CHO + H2O
Which statement about the final mixture of products is correct?
A
Both ethanal and water contain 3H atoms.
B
Ethanal is the only product containing 3H atoms.
C
Neither ethanal nor water contain 3H atoms.
D
Water is the only product containing 3H atoms.
28 Ethanedioic acid has the formula HO2CCO2H.
What is the formula of aluminium ethanedioate?
A
Al C2O4
B
Al (C2O4)3
C
Al 2C2O4
D
Al 2(C2O4)3
29 Which reaction gives butanoic acid as one of its products?
A
acid hydrolysis of butyl ethanoate
B
alkaline hydrolysis of butyl ethanoate
C
acid hydrolysis of ethyl butanoate
D
alkaline hydrolysis of ethyl butanoate
© UCLES 2021
9701/12/F/M/21
[Turn over
12
30 When reactant X is treated with a suitable reagent, products Y and Z are formed. Infrared spectra
of X, Y and Z are shown.
reactant X
transmittance
100
50
0
4000
3000
2000
1000
–1
wavenumber / cm
product Z
product Y
100
transmittance
transmittance
100
50
0
50
0
4000
3000
2000
1000
–1
wavenumber / cm
4000
3000
2000
1500
1000
–1
wavenumber / cm
Which row could be correct?
X
Y
Z
A
2,3-dimethylpent-2-ene
propanone
butanone
B
2-methylpent-2-ene
propanone
propanoic acid
C
pent-2-ene
ethanoic acid
propanoic acid
D
propyl propanoate
propan-1-ol
propanoic acid
© UCLES 2021
9701/12/F/M/21
500
13
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 A sample of 17.15 mol HI(g) is in dynamic equilibrium with 2.27 mol H2(g) and 2.84 mol I2(g) in a
volume of 1 m3 at 764 K and 141 kPa.
H2(g) + I2(g)
2HI(g)
Two equilibrium constants, Kc and Kp, can be calculated for this mixture.
Which statements about the equilibrium constants for this mixture are correct?
1
neither Kc nor Kp has any units
2
Kc = 45.6
3
Kc > Kp
32 An energy cycle for the combustion of methane is shown.
CH4(g) + 2O2(g)
∆H co CH4(g)
∆H of CH4(g)
CO2(g) + 2H2O(l)
∆H zo
C(s) + 2H2(g) + 2O2(g)
Which expressions can be used to calculate the energy change, ∆H zo ?
1
∆H of CH4(g) + ∆H co CH4(g)
2
∆H co C(s) + 2∆H co H2(g)
3
∆H co CO(g) + 2∆H co H2(g)
© UCLES 2021
9701/12/F/M/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
33 Many gases do not obey the general gas equation at high pressures.
Why is this?
1
At higher pressures the molecules have more energy.
2
At higher pressures the volume of the molecules is a larger proportion of the total volume.
3
At higher pressures the molecules experience greater intermolecular forces.
34 Which species can accept a lone pair of electrons to form a coordinate (dative covalent) bond?
1
BF3
2
H+
3
CH3+
35 A sample containing x mol of Al 2Cl 6 is dissolved in water to give solution W.
In order to precipitate all of the aluminium as its hydroxide, y mol of sodium hydroxide are
required.
More of the alkali is added to re-dissolve the precipitate, giving solution Z.
Which statements are correct?
1
the initial pH of solution W is below 7
2
y = 3x
3
Z contains x mol of aluminium
36 Nitrogen dioxide gas is produced when petrol is burned in car engines.
Which acids are made in the atmosphere as a result of this release of nitrogen dioxide into the
air?
1
H2SO3
2
H2SO4
3
HNO3
© UCLES 2021
9701/12/F/M/21
15
37 In which reactions is the major product formed by a nucleophilic substitution reaction?
1
bromoethane + potassium cyanide in ethanol
2
bromoethane + ammonia in ethanol under pressure
3
bromoethane + hot concentrated sodium hydroxide in ethanol
38 An excess of P reacts with Q, in the presence of concentrated sulfuric acid, to form R.
Effervescence is seen when a piece of sodium is added to pure R.
The structure of P is shown.
P
O
OH
OH
Which organic compounds could be compound Q?
O
1
OH
2
OH
3
O
39 Two carbonyl compounds have the molecular formula C3H6O.
Which reagents give different observations with these two compounds?
1
acidified aqueous potassium manganate(VII)
2
Fehling’s reagent
3
alkaline aqueous iodine
40 An organic compound, T, does not fizz when aqueous sodium carbonate is added to it.
Compound T contains 27.6% by mass of oxygen.
What could be the identity of T?
1
propanal
2
ethyl butanoate
3
3-methylpentanoic acid
© UCLES 2021
9701/12/F/M/21
Cambridge International AS & A Level
*9722650000*
CHEMISTRY9701/22
Paper 2 AS Level Structured Questions
February/March 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 12 pages.
IB21 03_9701_22/2RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1
The rate of chemical reactions is affected by changes in temperature and pressure.
(a) (i)
raw a curve on the axes to show the Boltzmann distribution of energy of particles in a
D
sample of gaseous krypton atoms at a given temperature.
Label the curve T1 and label the axes.
[2]
(ii)
On the diagram in (a)(i), draw a second curve to show the distribution of energies of the
krypton atoms at a higher temperature.
Label the second curve T2.[1]
(b) The Boltzmann distribution assumes that the particles behave as an ideal gas.
(i)State two assumptions of the kinetic theory as applied to an ideal gas.
1 ...........................................................................................................................................
..............................................................................................................................................
2 ...........................................................................................................................................
..............................................................................................................................................
[2]
(ii)
2.00 g of krypton gas, Kr(g), is placed in a sealed 5.00 dm3 container at 120 °C.
alculate the pressure, in Pa, of Kr(g) in the container.
C
Assume Kr(g) behaves as an ideal gas.
Show your working.
© UCLES 2021
pressure = ........................................ Pa [3]
9701/22/F/M/21
3
(iii)
State and explain the conditions at which krypton behaves most like an ideal gas.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(c) K
rypton reacts with fluorine in the presence of ultraviolet light to make krypton difluoride,
KrF2(g).
Kr(g) + F2(g) → KrF2(g)
activation energy for the reaction, Ea = +385 kJ mol–1
enthalpy change of formation of KrF2, ∆Hf = +60.2 kJ mol–1
(i)
Use this information to complete the reaction profile diagram for the formation of KrF2.
Label Ea and ∆Hf on the diagram.
Assume the reaction proceeds in one step.
energy
/ kJ mol–1
reactants
progress of reaction
[2]
(ii)
xplain, in terms of activation energy, Ea, and the collision of particles, how an increase in
E
temperature affects the rate of a chemical reaction.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
[Total: 14]
9701/22/F/M/21
[Turn over
4
2Chlorine, Cl 2, is a reactive yellow-green gas. It is a strong oxidising agent.
(a)State how Cl 2 is used in water purification.
.....................................................................................................................................................
............................................................................................................................................... [1]
(b) Chlorine has the highest first ionisation energy of the Period 3 elements Na to Cl.
(i)
Construct an equation for the first ionisation energy of chlorine.
Include state symbols.
........................................................................................................................................ [1]
(ii)
Explain the general increase in the first ionisation energies of the Period 3 elements.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/22/F/M/21
5
(c)The halide ions, X– (where X = Cl, Br, I), show clear trends in their physical and chemical
properties.
(i)
State and explain the relative thermal stabilities of the hydrogen halides, HX.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
The halide ions react easily with concentrated H2SO4.
The main sulfur-containing product of each reaction is shown in the table.
halide ion
Cl –
Br –
I–
main sulfur-containing product of
reaction with concentrated H2SO4
HSO4–
SO2
H 2S
oxidation number of sulfur
(ii)
omplete the table to show the oxidation number of sulfur in each of the sulfur-containing
C
products.[1]
(iii)
Explain why different sulfur-containing products are produced when each of these halide
ions reacts with concentrated H2SO4.
..............................................................................................................................................
........................................................................................................................................ [1]
(d)Cl 2 reacts with aqueous sodium hydroxide in a disproportionation reaction.
(i)
State what is meant by disproportionation.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Write an equation for the reaction of Cl 2 with cold aqueous sodium hydroxide.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/F/M/21
[Turn over
6
(e)Aluminium reacts with chlorine to form aluminium chloride.
luminium chloride can exist as the gaseous molecule Al 2Cl 6(g). This molecule contains
A
coordinate bonds.
(i)
Draw a diagram that clearly shows all the types of bond present in Al 2Cl 6(g).
[2]
(ii)
Describe what you would see when solid aluminium chloride reacts with water.
Name the type of reaction that occurs.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(f)0.020 mol of element Z reacts with excess Cl 2 to form 0.020 mol of a liquid chloride.
The liquid chloride has formula ZCl n, where n is an integer.
ZCl n reacts vigorously with water at room temperature to give an acidic solution and a white
solid.
When excess AgNO3(aq) is added to the solution, 11.54 g of AgCl (s) forms.
(i)
Suggest the type of bonding and structure shown by ZCl n.
........................................................................................................................................ [1]
(ii)Calculate the value of n in ZCl n.
© UCLES 2021
n = .............................. [2]
9701/22/F/M/21
7
(g) Dichloromethane, CH2Cl 2, is widely used as an organic solvent.
CH2Cl 2 can be prepared by reacting CH3Cl and Cl 2 at room temperature.
The reaction proceeds via several steps, as shown.
Cl 2
Cl • + CH3Cl
Cl 2 + •CH2Cl
Cl • + •CH2Cl
initiation
propagation 1
propagation 2
final step
2Cl •
HCl + •CH2Cl
products
CH2Cl 2
(i)Give the name of the mechanism of this reaction.
........................................................................................................................................ [1]
(ii)
State the essential condition required for the initiation step to take place.
........................................................................................................................................ [1]
(iii)
Give the electronic configuration of Cl •.
1s2 .................................................................................................................................. [1]
(iv)
Identify the products of the step labelled propagation 2.
........................................................................................................................................ [1]
(v)
Name the type of reaction shown in the final step.
........................................................................................................................................ [1]
(vi)
uggest the identity of another organic molecule that is a product of the reaction of CH3Cl
S
and Cl 2 under the same conditions.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 23]
9701/22/F/M/21
[Turn over
8
3Compounds P, Q and R have all been found in the atmosphere of one of Saturn’s moons.
P
Q
R
H
N
C
C
C
C
N
H
C
C
C
H
C
N
C
H
C
N
(a) The equation for the complete combustion of P, C4N2(l), is shown.
C4N2(l) + 4O2(g) → 4CO2(g) + N2(g)
(i)
∆H = –2036 kJ mol–1
The enthalpy change of formation, ∆Hf, of CO2(g) is –384 kJ mol–1.
Calculate the enthalpy change of formation, ∆Hf, of P, in kJ mol–1.
∆Hf of P = ............................. kJ mol–1 [2]
(ii)
One of the products of the complete combustion of P is nitrogen gas, N2(g).
Explain the lack of reactivity of nitrogen.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/F/M/21
9
(b)
Q forms when HCN reacts with ethyne, H
(i)
C
C
H.
Ethyne, HCN and Q are all weak Brønsted–Lowry acids.
Explain what is meant by the term weak Brønsted–Lowry acid.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)
Ethyne, HCN and Q all contain triple bonds between two atoms.
A triple bond consists of one sigma (σ) and two pi (π) bonds.
Draw a labelled diagram to show the formation of one pi (π) bond.
[2]
(c)
P and Q can be detected in the atmosphere by infrared spectroscopy.
Identify two absorptions, and the bonds that correspond to these absorptions, that will appear
in the infrared spectra of both P and Q.
1 ..................................................................................................................................................
.....................................................................................................................................................
2 ..................................................................................................................................................
.....................................................................................................................................................
[2]
© UCLES 2021
9701/22/F/M/21
[Turn over
10
(d) The flow chart shows some reactions of R.
R
H
H
C
C
reaction 1
C
H
H
H
C
C
H
C
N
reaction 3
dilute H2SO4(aq)
heat under reflux
reaction 2
S
N
H2(g)
T
CH3CH2CH2NH2
(i)
Name the type of reaction shown in reaction 1.
........................................................................................................................................ [1]
(ii)Draw the structure of S, the organic product of reaction 2.
[1]
(iii)
Name T.
........................................................................................................................................ [1]
(iv)
T can also be formed by the reaction of CH3CH2CH2Br with ammonia.
State the necessary conditions of this reaction.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 13]
9701/22/F/M/21
11
4
Hydroxyethanal, HOCH2CHO, has been observed in dust clouds near the centre of our galaxy.
hydroxyethanal
H
HO
C
O
C
H
H
(a) Predict the bond angles labelled x and y in the diagram of hydroxyethanal.
HO
x
H
O
C
C y
H
H
x = ..............................°
y = ..............................°
[2]
(b) Hydroxyethanal reacts separately with 2,4-dinitrophenylhydrazine (2,4-DNPH) and with Tollens’
reagent.
State what you would observe in each reaction.
reaction with 2,4-DNPH ..............................................................................................................
reaction with Tollens’ reagent .....................................................................................................
[2]
(c) H
ydroxyethanal is converted to ethanedioic acid, (CO2H)2, when it reacts with excess acidified
dichromate(VI) ions, Cr2O72–.
(i)
State the role of acidified Cr2O72– in this reaction.
........................................................................................................................................ [1]
(ii)
State and explain any other necessary conditions for this reaction to be successful.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/22/F/M/21
[Turn over
12
(d) Hydroxyethanal can be reduced to ethane-1,2-diol, (CH2OH)2, as shown.
hydroxyethanal
H
HO
C
H
(i)
O
C
ethane-1,2-diol
[H]
HO
H
H
H
C
C
H
H
OH
Write an equation for the reduction of hydroxyethanal to (CH2OH)2.
Use [H] to represent an atom of hydrogen from the reducing agent.
........................................................................................................................................ [1]
(ii)
Identify a reagent for this reduction reaction.
........................................................................................................................................ [1]
(iii)
(CH2OH)2 also forms when an alkene A reacts with cold, dilute, acidified manganate(VII)
ions.
Name A.
........................................................................................................................................ [1]
[Total: 10]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.
Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.
© UCLES 2021
9701/22/F/M/21
Cambridge International AS & A Level
*6430441026*
CHEMISTRY9701/42
Paper 4 A Level Structured Questions
February/March 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 28 pages. Any blank pages are indicated.
IB21 03_9701_42/2RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1
(a)The most common oxidation states of cobalt are +2 and +3.
Complete the electronic configurations of the following free ions.
●
Co2+ [Ar] ����������������������������������������������������������������������������������������������������������������������������
● Co3+ [Ar] ����������������������������������������������������������������������������������������������������������������������������
[1]
(b)Co2+ and Co3+ both form complexes with edta4–.
half-equation
Co3+ + e–
Eo/V
Co2+
O2 + 4H+ + 4e–
[Co(edta)]– + e–
Co2+ + 2e–
+1.82
2H2O
+1.23
[Co(edta)]2–
+0.38
Co
–0.28
Use the data in the table to predict what happens, if anything, when separate aqueous solutions
of Co3+ and [Co(edta)]– are left to stand in the air.
aqueous solution of Co3+
.....................................................................................................................................................
.....................................................................................................................................................
aqueous solution of [Co(edta)]–
.....................................................................................................................................................
.....................................................................................................................................................
[3]
© UCLES 2021
9701/42/F/M/21
3
(c)Hydrated cobalt(II) nitrate, Co(NO3)2•6H2O, is a red solid that behaves like hydrated
magnesium nitrate, Mg(NO3)2•6H2O, when heated.
Describe in detail what you would expect to observe when crystals of Co(NO3)2•6H2O are
heated in a boiling tube, gently at first and then more strongly.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(d) Explain why the thermal stability of the Group 2 nitrates increases down the group.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 8]
9701/42/F/M/21
[Turn over
4
2
(a)Iron(II) compounds are generally only stable in neutral, non-oxidising conditions.
It is difficult to determine the lattice energy of FeO experimentally.
(i)Use data from the Data Booklet and this Born–Haber cycle to calculate the lattice energy,
∆H latt, of FeO(s) in kJ mol–1.
Fe2+(g) + O2–(g)
Fe2+(g) + O(g) + 2e–
+798 kJ mol–1
–141 kJ mol–1
Fe2+(g) + O–(g) + e–
Fe (g) + O(g) + e
+
–
Fe(g) + O(g)
H latt
Fe(g) + 12O2(g)
Fe(s) + 12O2(g)
+416 kJ mol–1
–272 kJ mol–1
FeO(s)
© UCLES 2021
∆H lattFeO(s) = .............................. kJ mol–1 [2]
9701/42/F/M/21
5
(ii)
Most naturally occurring samples of iron(II) oxide are found as the mineral wüstite.
Wüstite has formula Fe20Ox. It contains both Fe2+ and Fe3+ ions.
90% of the iron is present as Fe2+ and 10% is present as Fe3+.
Deduce the value of x.
x = .............................. [1]
(iii)
tate and explain how the lattice energy of FeO(s) compares to the lattice energy of
S
CaO(s).
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/42/F/M/21
[Turn over
6
(b) Heating of FeO results in the formation of Fe3O4, as shown.
reaction 1
4FeO → Fe + Fe3O4
Each formula unit of Fe3O4 contains one Fe2+ and two Fe3+ ions.
(i)Show how reaction 1 can be described as a disproportionation reaction.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
Fe3O4(l) can be electrolysed using inert electrodes to form Fe.
(ii)
rite the half-equation for the reaction that occurs at the anode during the electrolysis of
W
Fe3O4(l).
........................................................................................................................................ [1]
(iii)
alculate the maximum mass of iron metal formed when Fe3O4(l) is electrolysed for
C
six hours using a current of 50 A.
Assume the one Fe2+ and two Fe3+ ions are discharged at the same rate.
© UCLES 2021
mass of iron = .............................. g [3]
9701/42/F/M/21
7
(c) LiFePO4 can be used in lithium-ion rechargeable batteries.
When the cell is charging, lithium reacts with a graphite electrode to form LiC6.
When the cell is discharging, the half-equations for the two processes that occur are as follows.
(i)
anode half-equation
LiC6 → 6C + Li+ + e–
cathode half-equation
Li+ + FePO4 + e– → LiFePO4
State one possible advantage of developing cells such as lithium-ion rechargeable
batteries.
........................................................................................................................................ [1]
(ii)
Use the cathode half-equation to determine the change, if any, in oxidation states of lithium
and iron at the cathode during discharging.
metal
change in oxidation state during discharging
from
to
lithium
iron
[1]
(iii)
Write the equation for the overall reaction that occurs when this cell is discharging.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 13]
9701/42/F/M/21
[Turn over
8
3Iodates are compounds that contain the IO3– anion.
(a)The IO3– anion is shown.
O
I
O–
O
Explain, with reference to the qualitative model of electron-pair repulsion, why the IO3– anion
has a pyramidal shape.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [1]
(b)The reaction of iodine and hot aqueous sodium hydroxide is similar to that of chlorine and
hot aqueous sodium hydroxide. Sodium iodate, NaIO3, is formed as one of the products.
Suggest an equation for the reaction of iodine and hot aqueous sodium hydroxide.
............................................................................................................................................... [1]
© UCLES 2021
9701/42/F/M/21
9
(c) The decomposition of hydrogen peroxide, H2O2, is catalysed by acidified IO3–.
H2O2 reduces acidified IO3– as shown.
5H2O2 + 2H+ + 2IO3– → I2 + 5O2 + 6H2O
This reaction is followed by the oxidation of I2 by H2O2.
half-equation
Eo/V
2H2O
+1.77
+ 3H2O
+1.19
H2O2
+0.68
H2O2 + 2H+ + 2e–
IO3– + 6H+ + 5e–
O2 + 2H+ + 2e–
1
2 I2
(i)Use the data to show that the separate reactions of H2O2 with IO3– and with I2 are both
feasible under standard conditions.
In your answer, give the equation for the reaction of H2O2 with I2.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [3]
(ii)Write the overall equation for the decomposition of H2O2 catalysed by acidified IO3–.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
[Turn over
10
(d)A student collects some data for the reaction of H2O2 with acidified IO3–, as shown in the table.
experiment
[H2O2]
/ mol dm–3
[IO3–]
/ mol dm–3
[H+]
/ mol dm–3
initial rate of reaction
/ mol dm–3 s–1
1
0.0500
0.0700
0.025
1.47 × 10–5
2
0.100
0.0700
0.050
2.94 × 10–5
3
0.100
0.140
0.025
5.88 × 10–5
4
0.150
0.140
0.025
8.82 × 10–5
(i)Use the data to determine the order of reaction with respect to [H2O2], [IO3–] and [H+].
Show your reasoning.
order with respect to [H2O2] = ..............................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
order with respect to [IO3–] = ...............................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
order with respect to [H+] = ..................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
[3]
(ii)Use your answer to (d)(i) to write the rate equation for this reaction.
rate = ���������������������������������������������������������������������������������������������������������������������������� [1]
© UCLES 2021
9701/42/F/M/21
11
(iii)Calculate the value of the rate constant, k, using data from experiment 4 and your answer
to (d)(ii).
Give the units of k.
k = ..............................
units = ..............................
[2]
(e) Pb(IO3)2 is only sparingly soluble in water at 25 °C.
The solubility product, Ksp, of Pb(IO3)2 is 3.69 × 10–13 mol3 dm–9 at 25 °C.
(i)
Write an expression for the solubility product of Pb(IO3)2.
Ksp =
[1]
(ii)Calculate the solubility, in mol dm–3, of Pb(IO3)2 at 25 °C.
solubility = .............................. mol dm–3 [2]
© UCLES 2021
9701/42/F/M/21
[Turn over
12
(f)NH4IO3 is an unstable compound that readily decomposes when warmed. The decomposition
reaction is shown.
NH4IO3(s) → 12 N2(g) + 12 O2(g) + 12 I2(g) + 2H2O(l)
(i)
∆H = –154.6 kJ mol–1
se the data in the table to calculate the entropy change of reaction, ∆S, of the decomposition
U
of NH4IO3(s).
compound
S / J K–1 mol–1
NH4IO3(s)
42
N2(g)
192
O2(g)
205
I2(g)
261
H2O(l)
70
∆S = .............................. J K–1 mol–1 [2]
(ii)This reaction is feasible at all temperatures.
Explain why, using the data in (f) and your answer to (f)(i).
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 18]
9701/42/F/M/21
13
4
The transition elements are able to form stable complexes with a wide range of molecules and ions.
(a) State the meaning of transition element.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [1]
(b) The d orbitals in an isolated transition metal ion are degenerate. In complexes, the d orbitals
occupy two energy levels.
(i)
Complete the diagram to show the arrangement of d orbital energy levels in octahedral
and in tetrahedral complexes.
energy
degenerate
d orbitals
octahedral
complex
isolated transition
metal ion
tetrahedral
complex
[1]
(ii)Sketch the shape of two d orbitals:
●
●
ne d orbital from the lower energy level in an octahedral complex
o
one d orbital from the higher energy level in an octahedral complex.
Use the axes below.
y
lower energy level
higher energy level
z
z
x
y
x
[2]
© UCLES 2021
9701/42/F/M/21
[Turn over
14
(c)Edds4– and edta4– are polydentate ligands that form octahedral complexes with Fe3+(aq).
edds4–
edta4–
CO2–
–
O2C
H
N
N
H
CO2–
CO2–
N
N
CO2
–
CO2–
CO2–
CO2–
The formulae of the complexes are [Fe(edds)]– and [Fe(edta)]– respectively.
(i)
n the diagram of edds4–, circle each atom that forms a bond to the Fe3+ ion in [Fe(edds)]–.
O
[1]
(ii)
[Fe(edds)]– is red and [Fe(edta)]– is yellow.
Explain why the two complexes have different colours.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)When edds4–(aq) is added to Fe3+(aq), the following reaction occurs.
[Fe(H2O)6]3+(aq) + edds4–(aq)
[Fe(edds)]–(aq) + 6H2O(l)
State the type of reaction that occurs.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
15
(iv)Write an expression for the stability constant, Kstab, of [Fe(edds)]–(aq).
Kstab =
[1]
(v)The table shows the values for the stability constants, Kstab, of both complexes.
complex
Kstab / mol–1 dm3
[Fe(edds)]–
3.98 × 1020
[Fe(edta)]–
1.26 × 1025
Predict which of the [Fe(edds)]– and [Fe(edta)]– complexes is more stable.
Explain your answer with reference to the Kstab value for each complex.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
(vi)When an excess of edta4–(aq) is added to [Fe(edds)]–(aq), the following equilibrium is
established.
[Fe(edds)]–(aq) + edta4–(aq)
[Fe(edta)]–(aq) + edds4–(aq)
Calculate the equilibrium constant, Kc, for this equilibrium, using the Kstab values given in
the table in (c)(v).
Kc = .............................. [1]
© UCLES 2021
[Total: 11]
9701/42/F/M/21
[Turn over
16
5
(a) Carboplatin and satraplatin are used as anticancer drugs instead of cisplatin.
carboplatin
satraplatin
O
O
NH3
O
Pt
O
O
NH3
Cl
Cl
O
Pt
NH3
N
O H2
O
(i)
Describe the action of cisplatin as an anticancer drug.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)
Suggest the geometry of the platinum centre in the carboplatin complex.
........................................................................................................................................ [1]
(iii)
Suggest why carboplatin does not show cis-trans isomerism.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
(iv)
Satraplatin is a neutral complex, containing the ligands CH3CO2–, C6H11NH2, Cl – and NH3.
Deduce the oxidation state of platinum in satraplatin.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
17
(b)Compound M is made from 1,3-dimethylbenzene in a two-step synthesis.
L
1,3-dimethylbenzene
M
O
step 1
C8H6O4
step 2
O
Cl
Cl
(i)Draw the structure of L.
[1]
(ii)
Suggest reactants and conditions for each step of this synthesis.
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
[2]
(iii)Write an equation for step 2.
........................................................................................................................................ [1]
(iv)
A student investigates a possible synthesis of M directly from benzene using COCl 2 in the
presence of an Al Cl 3 catalyst.
Benzene initially reacts with COCl 2 as shown.
reaction 1
COCl 2 + Al Cl 3 → Al Cl 4– + Cl
reaction 2
C6H6 + Cl
+
C
+
C
O
O → C6H5COCl + H+
Reaction 2 is the electrophilic substitution of Cl
+
C
O for H+ in benzene.
Suggest a mechanism for reaction 2.
[3]
© UCLES 2021
[Total: 12]
9701/42/F/M/21
[Turn over
18
6
Fumaric acid is a naturally occurring dicarboxylic acid.
fumaric acid
HO2C
CO2H
(a)Identify the products of the reaction between fumaric acid and an excess of hot, concentrated,
acidified manganate(VII).
............................................................................................................................................... [1]
(b) Fumaric acid can form addition and condensation polymers.
(i)Draw the repeat unit of the addition polymer poly(fumaric acid).
[1]
(ii)Draw the repeat unit of the polyester formed when fumaric acid reacts with ethane‑1,2‑diol,
(CH2OH)2.
The ester bond should be shown fully displayed.
[2]
(iii)
Explain why polyesters normally biodegrade more readily than polyalkenes.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
19
(c) Fumaric acid reacts with cold, dilute, acidified manganate(VII) to form compound P.
P
OH
CO2H
HO2C
OH
Only three stereoisomers of P exist. One of the stereoisomers is shown.
H
OH
CO2H
HO2C
OH
H
Complete the three-dimensional diagrams in the boxes to show the other two stereoisomers
of P.
HO2C
HO2C
[2]
© UCLES 2021
9701/42/F/M/21
[Turn over
20
(d)The enzyme fumarase catalyses the reaction of fumarate ions, C4H2O42–, with water to form
malate ions, C4H4O52–.
C4H2O42– + H2O
C4H4O52–
escribe, with the aid of a suitably labelled diagram, how an enzyme such as fumarase can
D
catalyse a reaction.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
[3]
© UCLES 2021
[Total: 10]
9701/42/F/M/21
21
7
Proline (Pro) is a naturally occurring amino acid.
proline
O
N
H
OH
(a) Proline is often found bonded to glycine (Gly) in a protein.
(i)
Draw the dipeptide Pro-Gly.
The peptide bond must be shown fully displayed.
[2]
(ii)Name the type of reaction that forms a dipeptide from two amino acids.
........................................................................................................................................ [1]
(iii)
Proline is able to form a poly(proline) peptide chain.
A section of a poly(proline) chain is shown.
N
N
O
N
O
O
Suggest why the secondary structure of poly(proline) cannot be stabilised by hydrogen
bonding.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
[Turn over
22
(b)The reaction scheme shows several reactions of proline.
proline
O
reaction 1
N
H
OH
NaOH(aq)
Q
reaction 3
reaction 2
CH3COCl
R
C7H11NO3
prolinol
N
H
OH
(i)Write an equation for the reaction of proline with NaOH(aq) in reaction 1.
C4H7NHCO2H + ����������������������������������������������������������������������������������������������������������� [1]
(ii)
Proline has a secondary amine functional group.
Secondary amines react with acyl chlorides. For example, dimethylamine reacts with
RCOCl according to the following equation.
dimethylamine
H 3C
H 3C
NCOR + HCl
NH + RCOCl
H3C
H3C
Suggest the skeletal structure of R, C7H11NO3, the product of reaction 2.
[1]
(iii)
Suggest the reagent required for reaction 3.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
23
(c) Proline was first synthesised in the laboratory using a multi-stage synthetic route.
In stage 1, CH2(CO2C2H5)2 and CH2=CHCN react to form a single product U.
U
CO2C2H5
stage 1
CH2(CO2C2H5)2 + CH2
CHCN
H
C
CO2C2H5
CH2CH2CN
(i)Name all the functional groups present in the reactants of stage 1.
CH2(CO2C2H5)2 .....................................................................................................................
CH2=CHCN ..........................................................................................................................
[2]
(ii)
Suggest the type of reaction that occurs in stage 1.
........................................................................................................................................ [1]
In stage 2, U reacts with reagent V to form W.
stage 2
H
U
W
CO2C2H5
CO2C2H5
C
CO2C2H5
reagent V
H
CH2CH2CN
(iii)
C
CO2C2H5
CH2CH2CH2NH2
Suggest a suitable reagent V.
........................................................................................................................................ [1]
Stage 3 takes place in the presence of an acid catalyst.
X and Y are the only products of the reaction.
W
X
O
CO2C2H5
stage 3
H
C
CO2C2H5
HN
CO2C2H5
+ Y
CH2CH2CH2NH2
(iv)
Suggest the type of reaction that occurs in stage 3.
........................................................................................................................................ [1]
(v)Deduce the identity of Y.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/F/M/21
[Turn over
24
After several further stages, Z is produced.
Z
Cl
CO2H
NH2
In the final stage of the synthesis, Z reacts via a nucleophilic substitution mechanism to form
proline.
(vi)
omplete the diagram to describe the reaction mechanism of the final stage. Draw curly
C
arrows, ions and charges, partial charges and lone pairs of electrons, as appropriate.
Draw the structure of any organic intermediate ion.
Z
proline
Cl
CO2H
CO2H
N
H
NH2
[3]
(vii)Identify with an asterisk (*) the chiral centre in proline.
CO2H
N
H
[1]
© UCLES 2021
9701/42/F/M/21
25
(d) Part of the structure of gelatin is shown.
O
C
H
N
H
C
CH3
O
C
H
N
H
O
C
C
H
N
H
N
H
C
O
C
H
N
H
O
C
C
H
CH2
CH2
H
N
H
C
O
C
H 2C
H 2C
CH2
N
O
CO2–
H
N
H
C
C
H
O
N
O
NH
C
C
C
+
NH2
NH2
Identify the number of amino acid units in the structure shown.
............................................................................................................................................... [1]
(e) (i)
At pH 6.5, proline exists in aqueous solution as a zwitterion.
Draw the structure of the zwitterion of proline.
Explain how the zwitterion of proline forms.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/42/F/M/21
[Turn over
26
(ii)The isoelectric point of an amino acid is the pH at which it exists as a zwitterion.
hree of the amino acids in gelatin are proline, alanine and glutamic acid. Their isoelectric
T
points are shown.
proline
alanine
glutamic acid
CO2H
amino acid
N
H
isoelectric point
CO2H
H 2N
6.5
CO2H
6.0
H 2N
CO2H
3.1
A mixture of these amino acids was analysed by electrophoresis using a buffer solution at
pH 4.0.
raw and label three spots on the diagram of the electropherogram to indicate the likely
D
position of each of these three species after electrophoresis.
Explain your answer.
–
+
mixture applied here
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [4]
© UCLES 2021
9701/42/F/M/21
27
(f)The weak acid ACES is a compound that can be used to make a buffer solution for electrophoresis
experiments.
ACES
O
H2 N
H
N
S
OH
O O
The anion of the sodium salt of ACES, C4H9N2O4SNa, is a strong base.
A buffer solution is prepared by the following steps.
●
●
●
.50 g of C4H9N2O4SNa is dissolved in 100 cm3 of distilled water.
3
50.0 cm3 of 0.200 mol dm–3 dilute hydrochloric acid is added to the solution.
The resulting mixture is transferred to a 250.0 cm3 volumetric flask, and the solution made
up to the mark.
C4H9N2O4SNa reacts with HCl with a 1 : 1 stoichiometry.
The pKa of ACES is 6.88 at 298 K.
Calculate the pH of the buffer solution formed at 298 K.
[Mr: C4H9N2O4SNa, 204.1]
pH = .............................. [4]
[Total: 28]
© UCLES 2021
9701/42/F/M/21
[Turn over
Cambridge International AS & A Level
CHEMISTRY
9701/11
Paper 1 Multiple Choice
May/June 2021
1 hour
You must answer on the multiple choice answer sheet.
*2679075838*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 06_9701_11/3RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
2
Which contains the largest number of hydrogen atoms?
A
0.10 mol of pentane
B
0.20 mol of but-2-ene
C
1.00 mol of hydrogen molecules
D
6.02  1023 hydrogen atoms
In which pair of species do both species have only one unpaired p electron?
Ar+ and C–
A
3
B
B and Ti+
C
F and Ga
D
Se– and Si–
Phosphorus forms two chlorides. Phosphorus(III) chloride, PCl 3, is a covalent liquid.
Phosphorus(V) chloride is an ionic solid. One of the ions present is [PCl 4]+.
What is the shape of the PCl 3 molecule and the [PCl 4]+ ion?
PCl 3
[PCl 4]+
A
pyramidal
square planar
B
pyramidal
tetrahedral
C
tetrahedral
square planar
D
trigonal planar
tetrahedral
© UCLES 2021
9701/11/M/J/21
3
4
is the standard enthalpy of formation of methane.
is the standard enthalpy of combustion of carbon.
is the standard enthalpy of combustion of hydrogen.
CH4(g) + 2O2(g)
Which expression is equivalent to
5
A
–
B
– 2
C
–
D
+ 2
CO2(g) + 2H2O(l)
?
+
–
+
–
The diagram shows the Boltzmann distribution for the same gas at two different temperatures, T1
and T2.
T1
T2
y
0
x
0
What is plotted on the y-axis and which line represents the higher temperature?
6
plotted on y-axis
higher temperature
A
number of molecules
T1
B
number of molecules
T2
C
molecular energy
T1
D
molecular energy
T2
What is the minimum mass of oxygen required to ensure the complete combustion of 12 dm3 of
propane measured under room conditions?
A
60 g
© UCLES 2021
B
80 g
C
120 g
9701/11/M/J/21
D
160 g
[Turn over
4
7
8
9
Why is the first ionisation energy of oxygen less than that of nitrogen?
A
The nitrogen atom has its outer electron in a different subshell.
B
The nuclear charge on the oxygen atom is greater than that on the nitrogen atom.
C
The oxygen atom has a pair of electrons in one p orbital that repel one another.
D
There is more shielding in an oxygen atom.
Which gas would behave most like an ideal gas under room conditions?
A
helium
B
nitrogen
C
ammonia
D
krypton
When hydrogen iodide is reacted with concentrated sulfuric acid, several reactions occur,
including:
8HI + H2SO4  H2S + 4H2O + 4I2
Which row gives the change in oxidation number of iodine and of sulfur in this reaction?
change in oxidation
number of iodine
change in oxidation
number of sulfur
A
–1
+6
B
–1
+8
C
+1
–6
D
+1
–8
© UCLES 2021
9701/11/M/J/21
5
10 The diagram represents the Haber process for the manufacture of ammonia from nitrogen and
hydrogen.
heat exchanger
N2 + H2
catalytic
converter
condenser
NH3
What is the purpose of the heat exchanger?
A
to cool the incoming gas mixture to avoid overheating the catalyst
B
to cool the reaction products and separate the NH3 from unused N2 and H2
C
to warm the incoming gas mixture and shift the equilibrium to give more NH3
D
to warm the incoming gas mixture and speed up the reaction
11 Which statement about catalysts is correct?
A
They change the reaction pathway by increasing the activation energy.
B
They increase the rate of reaction by lowering the enthalpy change of the reaction.
C
They increase the number of particles that have sufficient energy to react.
D
Heterogeneous catalysts are in the same state as the reactant.
12 Element X is in Period 3. Element X forms a solid oxide Y.
Y reacts with hot concentrated hydrochloric acid. Y reacts with hot aqueous sodium hydroxide to
form a compound in which X is part of an anion.
How many p electrons does one atom of X have in its outer shell?
A
0
© UCLES 2021
B
1
C
2
9701/11/M/J/21
D
3
[Turn over
6
13 The gaseous products of heating a mixture of Ca(OH)2 and NH4Cl are passed through solid CaO.
A single gaseous product, W, is collected.
A sample of W reacts with Cl 2(g) to produce two gases, X and Y.
X is an element. Y is acidic.
Y reacts with W to produce Z.
What are X and Z?
X
Z
A
N2
CaCl 2
B
N2
NH4Cl
C
O2
CaCl 2
D
O2
NH4Cl
14 Q is a mixture of a Group 2 oxide and a Group 2 sulfate. Q contains equal amounts of the two
compounds.
Q is shaken with water and the resulting mixture filtered; a solid residue is obtained. There is no
reaction when the solid residue is shaken with HCl (aq). Shaking the filtrate with H2SO4(aq)
produces a white precipitate.
What could be Q?
A
BaO + BaSO4
B
BaO + MgSO4
C
MgO + BaSO4
D
MgO + MgSO4
15 Which substance will not be a product of the thermal decomposition of hydrated
magnesium nitrate?
A
dinitrogen monoxide
B
magnesium oxide
C
oxygen
D
steam
© UCLES 2021
9701/11/M/J/21
7
16 A 5 cm3 sample of 0.05 mol dm–3 sodium chloride is mixed with a 5 cm3 sample of 0.05 mol dm–3
potassium iodide. 10 cm3 of acidified 0.05 mol dm–3 silver nitrate is then added, followed by
concentrated ammonia solution.
What is seen after the addition of an excess of concentrated ammonia solution?
A
a cream precipitate
B
a white precipitate
C
a yellow precipitate
D
no precipitate
17 The volatility of the Group 17 elements, chlorine, bromine and iodine, decreases down the group.
What is responsible for this trend?
A
bond length in the halogen molecule
B
bond strength in the halogen molecule
C
electronegativity of the halogen atom
D
number of electrons in the halogen atom
18 Acid rain is a dilute solution of sulfuric acid.
Which pollutant also contributes to the formation of acid rain?
A
carbon monoxide
B
carbon dioxide
C
nitrogen dioxide
D
hydrocarbons
19 R is an oxide of Period 3 element T. 5.00 g of R contains 2.50 g of T.
What is T?
A
magnesium
B
aluminium
C
silicon
D
sulfur
© UCLES 2021
9701/11/M/J/21
[Turn over
8
20 Bromoethane reacts with cyanide ions, producing propanenitrile.
Which statement about the SN2 mechanism of this reaction is correct?
A
The lone pair of electrons on C of CN– attacks the carbon atom of the C–Br bond.
B
The lone pair of electrons on C of CN– attacks the carbocation formed when the C–Br bond
breaks.
C
The lone pair of electrons on N of CN– attacks the carbon atom of the C–Br bond.
D
The lone pair of electrons on N of CN– attacks the carbocation formed when the C–Br bond
breaks.
21 Which compound would produce two different carboxylic acids when treated with hot,
concentrated, acidified manganate(VII) ions?
A
B
C
D
22 Which compound could show both cis-trans isomerism and optical isomerism?
A
B
Cl
Br
Cl
H
Br
C
C
Br
C
Br
C
I
H
Br
Br
C
Br
O
H
C
C
D
C
C
Br
C
limonene
What is the molecular formula of limonene?
C10H12
© UCLES 2021
B
C10H14
C
C10H16
9701/11/M/J/21
D
C10H18
H
C
C
Br
H
23 Limonene is a hydrocarbon found in the rind of citrus fruits.
A
Br
Cl
C
Cl
H
Cl
I
C
H
9
24 The compound cetyl palmitate, C15H31CO2C16H33, is a waxy solid.
Cetyl palmitate is heated under reflux with an excess of aqueous sodium hydroxide.
Which products will be formed?
A
C15H31ONa and C16H33CO2Na
B
C15H31CO2Na and C16H33ONa
C
C15H31OH and C16H33CO2Na
D
C15H31CO2Na and C16H33OH
25 When an organic compound is oxidised, any oxygen atom gained by the organic molecule is
considered to be from a water molecule also producing 2H+ + 2e–. Any hydrogen atom lost may
be considered to be lost as H+ + e–.
These changes can be represented by the following two equations.
H2O  [O] + 2H+ + 2e–
[H]  H+ + e–
Compound X is oxidised by heating under reflux with hot, acidified potassium dichromate(VI) for
one hour. The half-equation for the reduction reaction is shown.
Cr2O72– + 14H+ + 6e–  2Cr3+ + 7H2O
Under these conditions, one mole of potassium dichromate(VI) oxidises three moles of X.
What could X be?
A
propanal
B
propan-1-ol
C
propan-1,2-diol
D
propan-1,3-diol
© UCLES 2021
9701/11/M/J/21
[Turn over
10
26 Compound X has the empirical formula C2H4O. Its infra-red spectrum is shown.
100
transmittance / %
50
0
4000
3000
1500
2000
wavenumber / cm
1000
500
–1
What could be the skeletal formula of compound X?
A
B
D
C
OH
O
O
O
O
O
O
OH
H
27 How many moles of hydrogen, H2, are evolved when an excess of sodium metal is added to
one mole of citric acid?
citric acid
CO2H
HO
CH2CO2H
C
CH2CO2H
A
0.5
B
1.5
C
2
D
4
28 Which statement is correct for the reaction of carbonyl compounds with HCN?
A
The reaction is catalysed by concentrated H2SO4.
B
Pentan-2-one and HCN react to give a chiral product.
C
The reaction is a condensation reaction.
D
The reaction is nucleophilic substitution.
© UCLES 2021
9701/11/M/J/21
11
29 The table describes four reactions of propene.
Which row is correct?
reagent used
name of main
organic product
A
aqueous bromine
2-bromopropane
B
cold acidified aqueous potassium manganate(VII)
propane-1,3-diol
C
hydrogen chloride
2-chloropropane
D
steam
propan-1-ol
30 Butanoic acid is prepared from 1-bromopropane.
This synthesis requires a sequence of two reactions.
Which compound is prepared in the first stage of the synthesis?
A
1-aminopropane
B
propan-1-ol
C
butanal
D
butanenitrile
© UCLES 2021
9701/11/M/J/21
[Turn over
12
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 Ethanol combines with ethanoic acid to form ethyl ethanoate according to the following reaction.
C2H5OH(I) + CH3CO2H(I)
CH3CO2C2H5(I) + H2O(I)
∆H o = –6 kJ mol–1
9.2 g ethanol, 12 g ethanoic acid and 8.8 g ethyl ethanoate are mixed and allowed to stand at
298 K, until equilibrium is reached.
(Mr: C2H5OH, 46; CH3CO2H, 60; CH3CO2C2H5, 88)
The resulting equilibrium mixture is found to contain 4.8 g ethanoic acid.
The experiment is repeated at 323 K.
Which statements are correct?
1
There are 0.22 moles of ethyl ethanoate in the mixture at equilibrium at 298 K.
2
The equilibrium mixture at 323 K will contain more than 4.8 g of ethanoic acid.
3
If a small amount of water is added at the start of either experiment the value of Kc would not
be affected.
© UCLES 2021
9701/11/M/J/21
13
32 The diagram shows an incomplete energy profile diagram for a reaction.
products
enthalpy
reactants
progress of reaction
Which reactions could this diagram refer to?
1
CaCO3(s)  CaO(s) + CO2(g)
2
H2(g)  2H(g)
3
Cl –(aq)  Cl –(g) + aq
33 A gaseous hydrocarbon has a density of 2.42 g dm–3 under room conditions.
What could be the skeletal formula of this hydrocarbon?
1
2
3
34 Which molecules contain at least one bond angle of 120?
1
C2H4
2
PF5
3
NCl 3
35 Which statements are correct going across Period 3 from sodium to chlorine?
1
The charge on the nucleus increases, pulling the electrons closer to it.
2
The radius of the most common ion of each element decreases.
3
The shielding caused by inner electrons decreases, so the outer electrons are pulled closer
to the nucleus.
© UCLES 2021
9701/11/M/J/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
36 Which statements are correct?
1
Magnesium carbonate decomposes at a lower temperature than calcium carbonate.
2
Calcium hydroxide is more soluble in water than magnesium hydroxide.
3
Calcium is a stronger reducing agent than magnesium.
37 Which statements are correct?
1
1,1-difluoroethane is less reactive than 1,1-dichloroethane.
2
1,1-difluoroethane is polar.
3
The C–F bond is stronger than the C–Cl bond.
38 Which pairs of compounds may be distinguished by testing with alkaline aqueous iodine?
1
butanal and butanone
2
pentan-2-one and pentan-3-ol
3
propanone and propan-2-ol
39 Which reactions have a coloured organic product?
1
ethanal + 2,4-dinitrophenylhydrazine reagent
2
ethanol + acidified potassium dichromate(VI)
3
ethene + cold dilute acidified potassium manganate(VII)
40 Propanoic acid is reacted with an excess of lithium aluminium hydride. The organic product of this
reaction is reacted with ethanoic acid in the presence of concentrated sulfuric acid, forming
product X.
What are major commercial uses of X?
1
fuel
2
solvent
3
flavouring
© UCLES 2021
9701/11/M/J/21
Cambridge International AS & A Level
CHEMISTRY
9701/12
Paper 1 Multiple Choice
May/June 2021
1 hour
You must answer on the multiple choice answer sheet.
*2669587153*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages.
IB21 06_9701_12/3RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
2
3
Which statement about the Avogadro constant is correct?
A
It is the mass of one mole of any element.
B
It is the mass of 6.02  1023 atoms of any element.
C
It is the number of atoms in one mole of neon.
D
It is the number of atoms in 12 g of any element.
Which equation represents the first ionisation energy of iodine?
I2(g) + e–  I–(g)
A
1
2
B
I(g) + e–  I–(g)
C
1
2
D
I(g)  I+(g) + e–
I2(g)  I+(g) + e–
The structures represent three compounds, each with four carbon atoms per molecule.
X
O
Y
Z
O
O
O
OH
Which row is correct?
highest
boiling point
lowest
boiling point
A
X
Y
Z
B
Y
X
Z
C
Z
X
Y
D
Z
Y
X
© UCLES 2021
9701/12/M/J/21
O–Na+
3
4
The structural formula of alliin is shown.
alliin
H
H
xC
C
O
y
CH2
S
NH2
CH2
z
H
C
CO2H
H
What are the approximate bond angles x, y and z in a molecule of alliin?
5
x
y
z
A
90
90
109
B
120
109
90
C
120
120
109
D
180
109
109
Flask Q contains 5 dm3 of helium at 12 kPa pressure. Flask R contains 10 dm3 of neon at 6 kPa
pressure.
If the flasks are connected at constant temperature, what is the final pressure?
A
6
8 kPa
B
9 kPa
C
10 kPa
D
11 kPa
Sodium chloride, water and air represent three states of matter – solid, liquid and gas.
Which row is correct?
sodium chloride
water
air
A
particles held
in rigid structure
can easily be
compressed
can easily be
compressed
B
particles stationary
particles move
cannot easily be
compressed
C
particles stationary
particles stationary
particles move
D
resistant to
change of shape
cannot easily be
compressed
can easily be
compressed
© UCLES 2021
9701/12/M/J/21
[Turn over
4
7
The reaction pathway diagram for the catalysed reaction and the uncatalysed reaction between
N2 and H2 is shown.
N2(g) + 3H2(g)
2NH3(g)
Which letter represents the activation energy for the first step in the decomposition of NH3 in the
presence of a catalyst?
A
C
B
energy
N2(g) + 3H2(g)
D
2NH3(g)
reaction pathway
8
Nitrogen and oxygen can react together to form nitrogen monoxide, NO.
H = +180 kJ mol–1
N2 + O2  2NO
What is the bond energy of the bond between the atoms in NO?
A
9
630 kJ mol–1
B
810 kJ mol–1
C
1260 kJ mol–1
D
1620 kJ mol–1
The equation for a redox reaction is shown.
SnCl 2(aq) + 2HgCl 2(aq)  SnCl 4(aq) + Hg2Cl 2(s)
Which species is being oxidised in this reaction?
A
Sn2+
B
Cl –
C
Hg+
D
Hg2+
10 3.60 moles of hydrogen gas and 2.00 moles of iodine vapour are placed in a reaction vessel
which is then sealed and maintained at a constant temperature.
The equation for the reaction is shown.
H2 + I2
2HI
At equilibrium, 3.20 moles of hydrogen remain. All reactants and products are gaseous.
What is the value of Kp under these conditions?
A
0.0313
© UCLES 2021
B
0.125
C
0.156
9701/12/M/J/21
D
8.00
5
11 Two chemicals, X and Y, react together in solution to give product Z.
The rate of formation of product Z at the start of the reaction was measured in five experiments,
1–5, using various concentrations of X and Y. The results are shown.
experiment
number
starting concentration
of X / mol dm–3
starting concentration
of Y / mol dm–3
rate of formation of Z
at the start / mol dm–3 s–1
1
0.10
0.10
0.0001
2
0.10
0.20
0.0004
3
0.10
0.40
0.0016
4
0.20
0.10
0.0001
5
0.40
0.10
0.0001
Which statement is correct?
A
The rate of the reaction is directly proportional to the concentration of reagent X.
B
The rate of the reaction is directly proportional to the concentration of reagent Y.
C
The rate of the reaction is not affected by the concentration of reagent X.
D
The rate of the reaction is not affected by the concentration of reagent Y.
12 A sample of SiCl 4 is added to cold water.
Which statement describes the mixture formed at the end of the reaction?
A
acidic solution with no precipitate
B
acidic solution with white precipitate
C
neutral solution with no precipitate
D
neutral solution with white precipitate
13 L and M are elements in Period 3 of the Periodic Table.
●
The oxide of L is a solid at room temperature. This oxide has a giant structure.
●
The chloride of L does not react with water.
●
Argon is the only element in Period 3 with a lower melting point than M.
Which formula represents a compound of elements L and M?
A
Al 2S3
B
MgS
C
NaCl
D
PCl 5
14 A farmer requires a solid compound to raise the pH of the soil in a field from 5.5 to above 6.0.
Which compound could the farmer use?
A
(NH4)2SO4
© UCLES 2021
B
NH4NO3
C
Ca(OH)2
9701/12/M/J/21
D
Ca(NO3)2
[Turn over
6
15 Z is an anhydrous compound of a Group 2 element. When it is heated, Z undergoes thermal
decomposition to produce two different gases. Z has relatively low thermal stability compared to
other Group 2 compounds containing the same anion as Z.
What is compound Z?
A
barium carbonate
B
barium nitrate
C
magnesium carbonate
D
magnesium nitrate
16 Which row gives mixtures that both result in the oxidation of a halide ion?
mixture 1
mixture 2
A
AgNO3(aq) and NaCl (aq)
concentrated H2SO4(aq) and HI(aq)
B
Br2(aq) and NaCl (aq)
concentrated H2SO4(aq) and HCl (aq)
C
Cl 2(aq) and NaBr(aq)
CH3CHBrCH3(l) + NaOH (ethanolic)
D
Br2(aq) and NaI(aq)
concentrated H2SO4(aq) and NaBr(s)
17 Chlorine gas is widely used to treat contaminated water.
When chlorine is added to water, which chemical species present is responsible for killing
bacteria?
A
Cl O2–
B
Cl –
C
HCl
D
Cl O–
18 What is an environmental consequence of the uncontrolled use of nitrate fertilisers?
A
acid rain
B
low oxygen levels in streams
C
ozone depletion
D
the greenhouse effect
© UCLES 2021
9701/12/M/J/21
7
19 Ammonia gas, NH3, and hydrogen sulfide gas, H2S, react together to form the salt ammonium
sulfide, (NH4)2S. Ammonium sulfide dissolves in water to produce an orange alkaline solution.
(NH4)2S(aq)
NH3(aq) + NH4SH(aq)
The addition of NaOH(aq) to this solution produces a gas, X.
The addition of HCl (aq) to a separate portion of this solution produces a gas, Y.
X and Y could represent different gases or identical gases.
What are the identities of X and Y?
X
Y
A
H2S
H2S
B
H2S
NH3
C
NH3
H2S
D
NH3
NH3
20 Compound P is treated with an excess of hydrogen gas in the presence of a nickel catalyst. The
product Q is fully saturated.
compound P
What is the number of chiral carbon atoms in the product Q?
A
4
© UCLES 2021
B
5
C
6
9701/12/M/J/21
D
7
[Turn over
8
21 Hexadeca-10,12-dien-1-ol is produced by silk moths from hexadecanoic acid in a three-step
enzymic process.
hexadecanoic acid
O
OH
step 1
O
OH
step 2
O
OH
step 3
OH
Which row contains correct descriptions of the three steps?
step 1
step 2
step 3
A
elimination
elimination
dehydration
B
elimination
reduction
reduction
C
oxidation
elimination
oxidation
D
oxidation
oxidation
reduction
22 Compound X can be converted into compound Y in a single step.
compound Y
OH
X
O
O
What could be the identity of X?
A
© UCLES 2021
B
C
9701/12/M/J/21
D
9
23 Methane and bromine react by free radical substitution.
P and Q are involved in the reaction mechanism.
P and Q:
●
are both involved in propagation steps as reactants
●
are both involved in termination steps as reactants.
What could be P and Q?
A
Br and H
B
Br and CH3
C
Br and C2H6
D
CH3 and CH3Br
24 A few drops of 2-bromopropane were placed in a test-tube. An equal volume of aqueous
silver nitrate was added. A precipitate was formed.
The experiment was repeated with 2-iodopropane.
Which row is correct?
colour of precipitate from
2-bromopropane + AgNO3(aq)
faster rate of reaction
A
cream
2-bromopropane + AgNO3(aq)
B
yellow
2-bromopropane + AgNO3(aq)
C
cream
2-iodopropane + AgNO3(aq)
D
yellow
2-iodopropane + AgNO3(aq)
© UCLES 2021
9701/12/M/J/21
[Turn over
10
25 Sodium methoxide, Na+CH3O–, reacts with 2-chloro-2-methylpropane in a nucleophilic
substitution reaction. The nucleophile is the CH3O– ion.
Which row is correct?
intermediate or
transition state
product
A
(CH3)3C+
(CH3)3COCH3
B
(CH3)3C+
(CH3)3CCH2OH
CH3
H 3C
C
H3CO
C
–
HOCH2C(CH3)3
Cl
CH3
CH3
H 3C
D
H3CO
C
–
Cl
H3COC(CH3)3
CH3
26 Alcohol X reacts with concentrated sulfuric acid to produce a mixture of products.
Two of the products are structural isomers of each other.
What could be X?
A
hexan-2-ol
B
pentan-1-ol
C
pentan-3-ol
D
propan-2-ol
27 Which reaction will form a strong organic base?
A
ethanol and acidified sodium dichromate
B
ethanol and hot aluminium oxide
C
ethanol and sodium
D
ethanol and hydrogen chloride
© UCLES 2021
9701/12/M/J/21
11
28 Which reaction mechanism for the formation of C2H5CH(OH)(CN) is correct?
H+
O–
G–
O
H
G+
A
N
C–
OH
H
C
C
N
N
H
H+
O–
G–
O
H
G+
B
N
C–
OH
H
C
C
N
N
H
H+
O–
G+
O
H
G–
C
N
C–
OH
H
C
C
N
N
H
H+
O–
G–
O
H
G+
D
N
C–
OH
H
C
C
N
N
H
29 The synthesis shown may be used for the production of propan-1-ol.
step 1
compound X
N
step 2
OH
Which row gives the correct reagents for steps 1 and 2?
step 1
step 2
A
HCl (aq)
H2 + Ni
B
HCl (aq)
LiAl H4
C
NaOH(aq)
H2 + Ni
D
NaOH(aq)
NaBH4
© UCLES 2021
9701/12/M/J/21
[Turn over
12
30 The molecular formula of Z is C4H8O.
The infra-red spectrum of Z is shown.
100
transmittance / %
50
0
4000
3000
2000
1500
1000
500
wavenumber / cm–1
What could be Z?
A
B
O
C
OH
D
O
OH
© UCLES 2021
9701/12/M/J/21
OH
13
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 In which ions are the number of electrons equal to the number of neutrons?
1
19 
9F
2
31
15
3
23

11Na
P
32 Compound X is a straight chain hydrocarbon with an Mr of 84.
What can be determined about X?
1
empirical formula
2
molecular formula
3
whether X contains a C=C bond or not
© UCLES 2021
9701/12/M/J/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
33 When a sample of ammonium chloride is warmed it decomposes into ammonia and hydrogen
chloride gas.
NH4Cl (s)  NH3(g) + HCl (g)
cold surface
reaction 1
solid ammonium
chloride (reformed)
solid
ammonium chloride
heat
When the mixture of hot ammonia and hydrogen chloride gases hit a cold surface, a white solid of
ammonium chloride reforms.
Which statements are correct?
1
Reaction 1 is in dynamic equilibrium.
2
Reaction 1 is reversible.
3
Reaction 1 is an endothermic reaction.
34 Hydrogen chloride gas is formed by the reaction shown.
H2(g) + Cl 2(g)  2HCl (g)
What will change the average kinetic energy of the reacting gas particles?
1
increasing the temperature and increasing the concentration of hydrogen
2
cooling the reaction mixture and adding a catalyst
3
adding a catalyst and increasing the concentration of chlorine
© UCLES 2021
9701/12/M/J/21
15
35 Which oxides will cause a change in pH when added to water?
1
CaO
2
Al 2O3
3
SiO2
36 Which reaction routes can be used to make a pure sample of barium sulfate?
heat
in O2
1
Ba
2
Ba(NO3)2
strong
heat in air
3
Ba(OH)2
dilute
HNO3
product
dilute
HCl
solid an excess
product of water
product
dilute
H2SO4
product
dilute
H2SO4
product
filter, wash
and dry
product
dilute
H2SO4
product
filter, wash
and dry
product
filter, wash
and dry
37 Cortisone is a synthetic hormone.
cortisone
O
HO
OH
OH
H
H
H
O
Which classes of alcohol does this molecule contain?
1
primary alcohol
2
secondary alcohol
3
tertiary alcohol
38 Which changes are commonly involved in the formation of an addition polymer?
1
the formation of a -bond
2
the breaking of a -bond
3
the change in hybridisation of the orbitals of a carbon atom from sp2 to sp3
© UCLES 2021
9701/12/M/J/21
[Turn over
16
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
39 Which alcohols can be oxidised to form an organic compound which will give coloured
precipitates with both 2,4-dinitrophenylhydrazine reagent and alkaline aqueous iodine?
OH
1
OH
O
2
3
OH
40 Which mixtures form a carboxylic acid as one of the products?
O
1
+
O
H2SO4(aq)
o
O–
2
3
O
+
O
H2SO4(aq)
+
o
H2SO4(aq)
o
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.
Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.
© UCLES 2021
9701/12/M/J/21
Cambridge International AS & A Level
CHEMISTRY
9701/13
Paper 1 Multiple Choice
May/June 2021
1 hour
You must answer on the multiple choice answer sheet.
*9003800186*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 06_9701_13/2RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
Compound X is an organic compound that contains 30.6% carbon, 3.8% hydrogen, 20.4%
oxygen and 45.2% chlorine by mass.
What is the empirical formula of X?
A
2
C2H3OCl
B
C2H4OCl
C
C3H4OCl
D
C4H3O2Cl 2
A sample of propane, C3H8, with a mass of 9.61 g is completely combusted in an excess of
oxygen under room conditions.
Which volume of carbon dioxide gas is produced?
A
3
B
5.24 dm3
C
14.7 dm3
15.7 dm3
D
Which atom has the same number of electrons as an ammonium ion?
A
4
4.89 dm3
Mg
B
Na
C
Ne
D
O
Ethanal reacts with hydroxylamine, NH2OH, to form the molecule shown.
H
H
z
y
H
C
C
N
O
H
x
H
What is the order of increasing bond angle in this structure from smallest to largest?
A
z, x, y
© UCLES 2021
B
y, z, x
C
x, z, y
9701/13/M/J/21
D
z, y, x
3
5
Descriptions of the bonding in three substances are given.
substance 1
strong covalent bonds between
attractions between molecules
atoms,
permanent
dipole-dipole
substance 2
strong covalent bonds between atoms, weak forces between molecules
substance 3
strong covalent bonds between atoms, hydrogen bonding between
molecules
Which compounds could be substances 1, 2 and 3?
6
7
substance 1
substance 2
substance 3
A
CH3OH
Al 2Cl 6
CH2Cl 2
B
Al 2Cl 6
CH2Cl 2
CH4
C
CH2Cl 2
CH4
CH3OH
D
CH4
CH3OH
H2O
Which type of bonding is never found in elements?
A
covalent
B
ionic
C
metallic
D
van der Waals’ forces
Using the information in the table, what is the enthalpy change, q, for the reaction described?
Cs+(g) + Br –(g)  CsBr(s)
A
–636.9
© UCLES 2021
B
∆H = q kJ mol–1
standard
enthalpy change
value
/ kJ mol–1
o
H sol
CsBr(s)
+25.9
o
H hyd
Cs+(g)
–276
o
H hyd
Br –(g)
–335
–585.1
C
+585.1
9701/13/M/J/21
D
+636.9
[Turn over
4
8
Which enthalpy change is indicated by X in the enthalpy cycle shown?
C(s) + 2H2(g) + 2O2(g)
CH4(g)
CO2(g) + X
CH4(g)
CH4(g) + 2O2(g)
9
A
– 4  the enthalpy of combustion of hydrogen
B
+ 4  the enthalpy of combustion of hydrogen
C
– 2  the enthalpy of formation of water
D
+ 2  the enthalpy of formation of water
CO2(g) + 2H2O(l)
Copper dissolves in dilute nitric acid producing a blue solution of Cu(NO3)2, water and
nitrogen(II) oxide as the only products.
How many moles of acid react with three moles of copper in the balanced equation?
A
2
B
4
C
6
D
8
10 Nitrogen reacts with hydrogen to produce ammonia.
N2(g) + 3H2(g)
2NH3(g)
A mixture of 2.00 mol of nitrogen, 6.00 mol of hydrogen and 2.40 mol of ammonia is allowed to
reach equilibrium in a sealed vessel of volume 1 dm3. It is found that 2.32 mol of nitrogen were
present in the equilibrium mixture.
Which expression will give the value of Kc?
A
(1.76 )2
(2.32)(6.96)3
B
(1.76)2
(2.32)(6.32)3
C
(2.08 )2
(2.32)(6.32)3
D
(2.40)2
(2.32)(6.00)3
© UCLES 2021
9701/13/M/J/21
5
11 Nitric acid is produced by oxidising ammonia. The first step is to react ammonia with oxygen in
the presence of a catalyst to form nitrogen monoxide.
4NH3(g) + 5O2(g)
4NO(g) + 6H2O(g)
H = –1636 kJ mol–1
Which set of conditions will produce the greatest yield of nitrogen monoxide at equilibrium?
temperature
pressure
A
high
high
B
high
low
C
low
high
D
low
low
12 The height of the peak of the curve in a Boltzmann distribution represents the number of
molecules that have the most probable energy.
A sample of gas has its temperature decreased without changing the number of molecules
present.
Which statement correctly describes a feature of the Boltzmann distribution for the gas when the
temperature decreases?
A
The value of the most probable energy would stay the same.
B
The number of molecules with the most probable energy would increase.
C
The area under the molecular energy distribution curve would decrease.
D
The number of molecules at the very high energy end of the distribution would stay the
same.
13 Ammonia exists as simple covalent molecules, NH3. Ammonia can react with suitable reagents to
form products containing ammonium ions, NH4+. Ammonia can also react with suitable reagents
to form products containing amide ions, NH2–.
Which of these nitrogen-containing species are present in an aqueous solution of ammonia?
A
ammonia molecules and amide ions
B
ammonia molecules and ammonium ions
C
ammonia molecules only
D
ammonium ions only
© UCLES 2021
9701/13/M/J/21
[Turn over
6
14 Which problem can result if too much NH4NO3 is applied to crops by farmers?
A
Not all the NH4NO3 is used by plants and the excess makes the soil alkaline.
B
Rain washes some of the NH4NO3 into rivers where it forms a precipitate.
C
Some of the NH4NO3 dissolves in groundwater which may eventually be used for drinking.
D
Ammonia is produced; this lowers the pH of the soil.
15 When descending Group 17 from chlorine to iodine, which statement is correct?
A
The hydrides become less thermally stable as they become weaker reducing agents.
B
The hydrides become more thermally stable as the reactivity of the elements decreases.
C
The volatility of the elements decreases as the van der Waals’ forces increase.
D
The volatility of the elements increases as the size of the molecules increases.
16 A powder is known to be either a single sodium halide or a mixture of two sodium halides.
A sample of the powder was dissolved in water.
Aqueous silver nitrate was added, and a pale yellow precipitate was formed. When concentrated
aqueous ammonia was then added, this precipitate partly dissolved leaving a darker yellow
precipitate.
What could the powder be?
A
sodium bromide only
B
sodium iodide only
C
a mixture of sodium chloride and sodium bromide
D
a mixture of sodium chloride and sodium iodide
17 Which statement is correct?
A
Doctors can use the very insoluble MgSO4 to investigate the digestive system.
B
Farmers can lower the pH of soil by spreading CaCO3 on it.
C
Students can test a solution for SO42– ions by using Ba(NO3)2(aq) followed by HNO3(aq).
D
The insoluble hydroxide, Ba(OH)2, can be safely used to lower the acidity of the stomach.
© UCLES 2021
9701/13/M/J/21
7
18 A solid, X, was placed in an excess of the liquid Y.
A colourless gas was given off and a white precipitate was seen. The precipitate was not X.
What could be the identities of X and Y?
X
Y
A
BaCO3
H2O
B
Ca
dilute H2SO4
C
Mg
dilute H2SO4
D
SrCO3
dilute HCl
19 Two oxides of Period 3 elements are added separately to water. Both react to form colourless
solutions. One solution is alkaline, the other is acidic.
What could be the two oxides?
A
Al 2O3 and SiO2
B
Al 2O3 and P4O10
C
Na2O and P4O10
D
Na2O and SiO2
20 Which compound shows stereoisomerism?
A
2-methylbut-2-ene
B
2-chloropropan-1-ol
C
difluorochlorobromomethane
D
pent-1-ene
21 Two carbon-containing products result from the reaction of alkene Z with a hot, concentrated,
acidified solution of potassium manganate(VII).
One product forms an orange precipitate with 2,4-dinitrophenylhydrazine reagent. The other
product is a gas which gives a white precipitate with aqueous calcium hydroxide.
Which alkene could be alkene Z?
A
but-2-ene
B
2-methylpropene
C
2-methylbut-2-ene
D
propene
© UCLES 2021
9701/13/M/J/21
[Turn over
8
22 What is the correct mechanism for the addition of hydrogen bromide to ethene?
H
A
H
C
H
C
Br G
HG
+
C
H
+
HG
H
Br G
+
H
H
C
C
Br
H
H
H
H
H
H
H
H
C
C+
C
C
H
H
Br
Br
–
H
H
H
H
H
H
H
H
H
H
C
C+
C
C
H
H
H
Br
–
H
Br
H
H
H
H
H
H
H
H
C
C+
C
C
H
H
–
H
C
H
–
Br
C
HG
D
C+
H
–
H
C
C
H
H
C
Br G
C
H
–
H
B
H
H
C
H
Br
Br–
H
+
HG
Br G
H
H
H
–
23 Halogenoalkanes react with nucleophiles such as OH–.
Which pair of halogenoalkanes both react via an SN1 mechanism?
A
B
Cl
Br
and
and
Br
C
Cl
D
Br
Br
© UCLES 2021
and
Cl
9701/13/M/J/21
and
Br
9
24 A mixture of ethanol and methanol is burned in oxygen to produce 35 cm3 of CO2 and 55 cm3 of
H2O.
Complete combustion occurs and the volumes of both products are measured at 101 kPa and
120 C.
What is the molar ratio, ethanol : methanol, in the mixture?
A
1:3
B
2:3
C
3:2
D
3:1
25 Two reactions are shown. Only one product is identified in each reaction.
ethanol + acidified Cr2O72–  ethanal
ethanol + sodium  sodium ethoxide
Which statement about these reactions is correct?
A
The formations of both ethanal and sodium ethoxide are redox reactions.
B
The formations of both ethanal and sodium ethoxide result in colour changes.
C
The formation of ethanal is catalysed by potassium dichromate.
D
The formation of sodium ethoxide is a dehydration reaction.
26 The skeletal formulae of three compounds are shown.
R
O
S
T
OH
O
O
O
Which compounds will give a positive test with 2,4-dinitrophenylhydrazine reagent?
A
R only
© UCLES 2021
B
R and S only
C
S and T only
9701/13/M/J/21
D
R, S and T
[Turn over
10
27 The diagram shows the structure of a compound formed by the reaction of HCN with a carbonyl
compound, X.
C 4H 9
H 3C
C
CN
OH
What is the mechanism of this reaction and what is the functional group in X?
mechanism of reaction
functional group in X
A
electrophilic addition
aldehyde
B
electrophilic addition
ketone
C
nucleophilic addition
aldehyde
D
nucleophilic addition
ketone
28 Compound Y is treated with a single reagent under suitable conditions. 2-methylbutanoic acid is
produced.
What could compound Y be?
A
pentan-2-one
B
2-methylbutan-2-ol
C
2-methylbutanenitrile
D
methylpropanenitrile
29 Two reactions are shown.
(CH3)2CHCO2H
CH3CO2CH(CH3)2
LiAl H4
hydrolysis
To which classes of alcohol do P and Q belong?
P
Q
A
primary
primary
B
primary
secondary
C
secondary
primary
D
secondary
secondary
© UCLES 2021
9701/13/M/J/21
alcohol P
alcohol Q + acid R
11
30 The infra-red spectrum of molecule Z is shown.
100
transmittance / %
50
0
4000
3000
1500
2000
1000
500
wavenumber / cm–1
What could be the identity of Z?
B
A
HO
O
O
HO
O
© UCLES 2021
OH
O
O
O
C
D
O
O
O
O
9701/13/M/J/21
O
[Turn over
12
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 Which statements about first ionisation energies are correct?
1
They are always endothermic.
2
They decrease down Group 2.
3
They decrease across Period 3.
32 The equation shows the decomposition of three moles of an ion containing chromium in an acid
solution.
3CrO43–(aq) + 8H+(aq)  2CrO42–(aq) + Cr3+(aq) + 4H2O(l)
Which statements are correct?
1
One mole of CrO43– is reduced.
2
Two moles of CrO43– are oxidised.
3
Three moles of electrons are transferred.
33 Disaccharides are hydrolysed in slightly acidic solutions. This reaction is very slow.
A biological catalyst is added to a slightly acidic mixture of three disaccharides, sucrose, maltose
and lactose. The hydrolysis reaction remains slow for sucrose and maltose but is now much
faster for lactose.
Which statements about the catalyst are correct?
1
The catalyst increases the activation energy of all three hydrolysis reactions.
2
The catalyst shows specificity.
3
The hydrolysis of lactose using a catalyst has a different mechanism to the hydrolysis of
lactose without a catalyst.
© UCLES 2021
9701/13/M/J/21
13
34 Element X is a solid under room conditions. It occurs as a contaminant of fossil fuels.
Its oxide, Y, is formed when fossil fuels are burned.
In the atmosphere, Y can be further oxidised to Z.
Which statements about X, Y and Z are correct?
1
Atoms of X have paired p electrons.
2
The atmospheric oxidation of Y to Z is a catalysed reaction.
3
With water, Z forms a strong acid.
35 Which reagents produce a solution of sodium chlorate(V)?
1
chlorine and hot concentrated sodium hydroxide solution
2
chlorine and cold dilute sodium hydroxide solution
3
chlorine dissolved in water at room temperature
36 Which statements help to explain the increase in melting point from sodium to aluminium?
1
The charge on the metal ion increases.
2
There are more delocalised electrons per metal ion.
3
The radius of the metal ion decreases.
37 The diagram shows a molecule of a compound used as a flame retardant.
Br
Br
Br
Br
Br
Br
Which statements about this structure are correct?
1
Each brominated C atom is chiral.
2
The molecular formula is C12H20Br6.
3
The C–C–C bond angles are all 120.
© UCLES 2021
9701/13/M/J/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
38 Bromoethane reacts with NaOH in different ways depending on the solvent used.
Which rows about these reactions are correct?
solvent used
organic product
1
water
ethan-1,2-diol
2
ethanol
ethene
3
water
ethanol
39 Three compounds, X, Y and Z, are shown.
X
Y
Z
C2H5COCH3
C2H5CHO
CH3CO2H
Which statements about X, Y and Z are correct?
1
X reacts with alkaline aqueous iodine.
2
Y reacts with Tollens’ reagent.
3
Z does not react with alkaline aqueous iodine.
40 5-hydroxypentanoic acid is readily converted into the cyclic compound L.
L
O
O
Which statements about this reaction are correct?
1
Acidified sodium dichromate(VI) is used as a reagent.
2
A water molecule is produced in the reaction.
3
The reaction can be catalysed by concentrated H2SO4.
© UCLES 2021
9701/13/M/J/21
Cambridge International AS & A Level
*5348916287*
CHEMISTRY9701/21
Paper 2 AS Level Structured Questions
May/June 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 12 pages. Any blank pages are indicated.
IB21 06_9701_21/3RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1Ethanedioic acid, HO2CCO2H, has a relative molecular mass of 90.0.
(a) (i)Explain what is meant by the term relative molecular mass.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)State the empirical formula of ethanedioic acid.
........................................................................................................................................ [1]
(iii)Calculate how many atoms of carbon are present in 0.18 g of ethanedioic acid, HO2CCO2H.
Show your working.
atoms of carbon present = .............................. [3]
(b)
Solid ethanedioic acid reacts with aqueous calcium ions to make a precipitate of
calcium ethanedioate, CaC2O4.
CaC2O4 breaks down when heated to form calcium oxide, carbon dioxide and carbon monoxide.
(i)Construct an equation to represent the reaction of CaC2O4 when heated. Include state
symbols.
........................................................................................................................................ [2]
(ii)Identify the type of reaction which occurs when CaC2O4 is heated.
........................................................................................................................................ [1]
(iii)Identify another compound containing calcium ions which will also produce carbon dioxide
and calcium oxide when it is heated.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 10]
9701/21/M/J/21
3
2Carbon monoxide gas, CO(g), and nitrogen gas, N2(g), are both diatomic molecules.
(a)The diagram shows the arrangement of outer electrons in a molecule of CO(g).
C
O
(i)State one similarity and one difference in the way the atoms in a carbon monoxide
molecule are bonded together compared to the atoms in a nitrogen molecule.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)The table states the electronegativity values of carbon, nitrogen and oxygen atoms.
electronegativity
C
N
O
2.5
3.0
3.5
Use the electronegativity values and relevant details from the Data Booklet to complete
the table below.
N2
CO
number of electrons per
molecule
type(s) of intermolecular
(van der Waals’) force
[2]
(b)N2(g) is less reactive than CO(g) even though N2(g) has a lower bond energy than CO(g).
Suggest why CO(g) is more reactive than N2(g).
.....................................................................................................................................................
............................................................................................................................................... [1]
© UCLES 2021
9701/21/M/J/21
[Turn over
4
(c)Both carbon monoxide and nitrogen are gases at room temperature and pressure.
They both behave like ideal gases under certain conditions.
(i)State the two conditions necessary for these two gases to approach ideal gas behaviour.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Explain why N2(g) behaves more like an ideal gas than CO(g) does at 20.0 °C and 101 kPa.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(d)Calculate the amount, in mol, of pure nitrogen gas which occupies 100 cm3 at 101 kPa and
20.0 °C.
Use relevant information from the Data Booklet. Show your working.
Assume nitrogen behaves as an ideal gas.
.............................. mol
[3]
© UCLES 2021
[Total: 11]
9701/21/M/J/21
5
3Sodium halide salts react with concentrated sulfuric acid at room temperature.
(a) (i)Write an equation to represent the reaction of NaCl (s) with concentrated sulfuric acid.
........................................................................................................................................ [1]
(ii)Name this type of reaction.
........................................................................................................................................ [1]
(b)NaI(s) reacts with concentrated sulfuric acid, at room temperature, to form steamy fumes.
(i)Identify the chemical responsible for the steamy fumes.
........................................................................................................................................ [1]
(ii)The reaction of NaI(s) with concentrated sulfuric acid continues, forming several other
products, including a dark grey solid.
Identify the chemical responsible for the dark grey solid and one other product of this
further reaction.
dark grey solid .....................................................................................................................
other product .......................................................................................................................
[2]
(c)Explain the differences in observations, at room temperature, when NaI(s) reacts with
concentrated sulfuric acid compared to those for NaCl (s).
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(d)
Complete the equation for the reaction of Br – with excess concentrated H2SO4 at room
temperature.
......Br – + ......H+ + ......H2SO4 → ...............................................................................
[1]
© UCLES 2021
[Total: 8]
9701/21/M/J/21
[Turn over
6
4Aqueous bromine reacts with methanoic acid to form hydrogen bromide and carbon dioxide gas.
Br2(aq) + HCO2H(aq) → 2HBr(aq) + CO2(g)
The table shows the oxidation numbers of bromine and carbon in the species involved in this
reaction.
Br in Br2
C in HCO2H
Br in HBr
C in CO2
0
+2
–1
+4
oxidation number
(a)Identify the oxidising agent in this reaction. Explain your reasoning with reference to oxidation
numbers.
.....................................................................................................................................................
............................................................................................................................................... [1]
(b)Suggest one change you would observe, ignoring temperature changes, when bromine reacts
with methanoic acid.
............................................................................................................................................... [1]
(c)This reaction can be followed by measuring the concentration of bromine present in the mixture
at regular time intervals.
The graph shows the change in concentration of bromine against time in a reaction carried out
at 20 °C.
100
80
[Br2] 105
/ mol dm–3
60
40
20
0
0
100 200 300 400 500 600
time / s
(i)Use the graph to calculate the average rate of reaction at 20 °C during the first 600 s. State
the units of this rate of reaction.
average rate of reaction .............................................. units ..............................................
[2]
© UCLES 2021
9701/21/M/J/21
7
The experiment is repeated at a temperature of 40 °C. This relatively small increase in
temperature produces a large increase in reaction rate.
(ii)Sketch a graph, on the same axes, to show the expected results when repeating the
experiment at 40 °C.[1]
(iii)
The rate of reaction increases when the frequency of successful collisions between
reactant particles increases.
Explain why an increase in temperature produces this effect.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(d)Complete the ‘dot-and-cross’ diagram, showing outer electrons only, to show the bonding in
methanoic acid, HCO2H.
O
C
H
O
H
[2]
© UCLES 2021
[Total: 9]
9701/21/M/J/21
[Turn over
8
5
(a)Naphtha is a mixture which contains only hydrocarbon molecules.
(i)What is meant by the term hydrocarbon?
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Name the raw material that is used to produce a sample of naphtha.
........................................................................................................................................ [1]
(b)Compound V is found in naphtha. It has a molecular formula C10H22.
When V is heated at high pressure in the absence of air, an equal number of moles of ethene,
propene and W are made. W is a compound made of straight chain, saturated molecules.
(i)Name the process that describes this reaction.
........................................................................................................................................ [1]
(ii)Deduce the structure of W. Draw its structure below.
[1]
(c)Propene is separated from the mixture and heated in air in the presence of a catalyst. Propene
is oxidised to X, which contains two functional groups.
(i)Effervescence is seen when Na2CO3(aq) is added to X.
Identify the functional group present in X which is responsible for this observation.
........................................................................................................................................ [1]
(ii)Identify a reagent which could be used to show that X contains a C=C. Include relevant
observations.
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/21/M/J/21
9
(d)
X reacts with another reagent to form Y.
Molecules of Y react together to form addition polymer Z. The diagram shows the repeat unit
of polymer Z.
repeat unit of polymer Z
O
O– Na+
Draw the structural formula of monomer Y.
[1]
(e)Polymer Z is useful because it absorbs large amounts of water. However, there are problems
associated with the disposal of products containing polymer Z.
Combustion is not an appropriate method to dispose of pure Z because the process releases
harmful gases. Some of these gases contribute to the enhanced greenhouse effect.
(i)Identify a gas released during the combustion of Z which contributes to the enhanced
greenhouse effect.
........................................................................................................................................ [1]
(ii)Identify another gas which could be produced during the combustion of pure Z. Describe
a consequence, other than the enhanced greenhouse effect, of its release into the
atmosphere.
gas .......................................................................................................................................
consequence .......................................................................................................................
[1]
© UCLES 2021
[Total: 10]
9701/21/M/J/21
[Turn over
10
6Propene, C3H6, reacts with H2O in the presence of an acid catalyst to form an alcohol with molecular
formula C3H8O.
(a)Name this type of reaction.
............................................................................................................................................... [1]
(b)Name the catalyst used and state the conditions needed for this reaction to occur.
catalyst .......................................................................................................................................
conditions ...................................................................................................................................
[2]
(c)Complete the table to show the numbers of sigma (σ) bonds and pi (π) bonds present in
propene, C3H6, and C3H8O.
σ
π
C3H6
C 3H 8O
[2]
(d)The reaction of propene, C3H6, with H2O occurs in a two-step mechanism. In step 1 C3H6 reacts
with the catalyst, H+, to form a carbocation.
(i)Draw structures to identify the more stable and less stable carbocations which can form in
step 1. Explain your answer.
more stable carbocation
less stable carbocation
explanation ..........................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
[3]
© UCLES 2021
9701/21/M/J/21
11
(ii)Name the major organic product formed from the reaction of propene, C3H6, with H2O.
........................................................................................................................................ [1]
(e)2-bromopropane reacts to form propene, hydrogen bromide and water under certain conditions.
(i)Name this type of reaction.
........................................................................................................................................ [1]
(ii)Describe the reagents and conditions needed to favour this reaction.
reagents ...............................................................................................................................
conditions ............................................................................................................................
[2]
© UCLES 2021
[Total: 12]
9701/21/M/J/21
[Turn over
Cambridge International AS & A Level
*6703041968*
CHEMISTRY9701/22
Paper 2 AS Level Structured Questions
May/June 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 12 pages. Any blank pages are indicated.
IB21 06_9701_22/4RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1A Group 2 metal combines with bromine to form a crystalline solid, MBr2.
Excess aqueous AgNO3 is added to a solution of MBr2 and a precipitate forms. The mixture is
filtered. The precipitate is dried and the mass of the precipitate is recorded.
(a)State the formula and colour of the precipitate.
............................................................................................................................................... [2]
(b)Complete the equation to represent the reaction between MBr2 and AgNO3.
......MBr2 + ......AgNO3 → ...................................................................
[1]
(c)A 0.250 g sample of pure MBr2 contains 8.415 × 10–4 mol MBr2.
Calculate the relative formula mass, Mr, of MBr2. Use this to identify M.
Show your working.
Mr = ..............................
M = ..............................
[3]
(d)A sample of MBr2 is dissolved in water. Chlorine gas is then bubbled into the solution.
(i)Describe the observations for this reaction.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Name the type of reaction that occurs when MBr2 reacts with chlorine gas.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/M/J/21
3
(e)Compound Y is a pure insoluble solid which contains halide ions.
A single reagent is added directly to compound Y to determine the halide ion present.
Identify the reagent added. State the observation which would confirm that Y contains bromide
ions.
reagent .......................................................................................................................................
observation .................................................................................................................................
[2]
(f)Separate 1.0 g samples of three different magnesium salts are tested in order to identify the
anion present in each sample.
(i)Explain how the action of heat is used to identify which sample is:
●
●
●
MgCO3
Mg(NO3)2
MgO.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [3]
(ii)Complete the electron configuration of the magnesium cation present in these salts.
1s2 .................................................................................................................................. [1]
(g)A sample of MgCO3(s) is distinguished from a sample of Mg(OH)2(s) by adding a small amount
of each solid to HCl (aq).
State one similarity and one difference in these two reactions.
similarity ......................................................................................................................................
.....................................................................................................................................................
difference ....................................................................................................................................
.....................................................................................................................................................
[2]
© UCLES 2021
[Total: 16]
9701/22/M/J/21
[Turn over
4
2The strength of interaction between particles determines whether the substance is a solid, liquid or
gas at room temperature.
(a)Lithium sulfide, Li2S, is a crystalline solid with a melting point of 938 °C. It conducts electricity
when it is molten.
(i)Give the formulae of the particles present in solid lithium sulfide.
........................................................................................................................................ [1]
(ii)Explain, in terms of the structure of the crystalline solid, why lithium sulfide has a high
melting point.
..............................................................................................................................................
........................................................................................................................................ [2]
(b)Carbon monoxide, CO, is a gas at room temperature and pressure. It contains a coordinate
bond.
(i)Explain what is meant by coordinate bond.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Draw a ‘dot-and-cross’ diagram to show the arrangement of outer electrons in CO.
Show the electrons belonging to the C atom as ×.
Show the electrons belonging to the O atom as ●.
[2]
© UCLES 2021
9701/22/M/J/21
5
(c)Nitrogen, N2, is also a gas at room temperature and pressure. Neither CO nor N2 is an ideal
gas.
(i)State two assumptions that are made about the behaviour of particles in an ideal gas.
1 ...........................................................................................................................................
..............................................................................................................................................
2 ...........................................................................................................................................
..............................................................................................................................................
[2]
(ii)Explain why N2 does not behave as an ideal gas at very high pressures.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)Complete the table by naming all the types of intermolecular forces (van der Waals’) in
separate samples of N2(g) and CO(g).
N2(g)
CO(g)
number of electrons per molecule
14
14
presence of a dipole moment


–195.8
–191.5
boiling point / °C
intermolecular forces (van der Waals’)
[2]
(iv)Suggest why the bond in a molecule of CO contains a dipole moment.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 13]
9701/22/M/J/21
[Turn over
6
3A large excess of 2-bromo-2-methylpropane is added to 0.0010 mol of NaOH(aq), which contains
a few drops of phenolphthalein indicator. A stopwatch is started as soon as the substances are
mixed. The time taken for the pink colour to disappear is recorded.
The experiment is repeated at different temperatures, keeping all concentrations and volumes of
reagents constant.
temperature
/ °C
time taken for
pink colour to disappear / s
20
300
25
65
35
20
(a)Explain what is meant by the term rate of reaction.
.....................................................................................................................................................
............................................................................................................................................... [1]
(b)The graph shows the energy distribution of molecules in a sample of 2‑bromo‑2‑methylpropane
at 25 °C.
Ea represents the activation energy for the reaction.
proportion
of molecules
with a given
energy
0
0
Ea
molecular energy
(i)Label the graph to show the proportion of 2‑bromo‑2‑methylpropane molecules which
have sufficient energy to react.
[1]
(ii)Use the same axes to sketch the distribution of energies of molecules in a sample of
2‑bromo‑2‑methylpropane at 50 °C.[2]
(iii)State the effect of an increase in temperature on Ea for this reaction.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/M/J/21
7
(c) (i)Draw the mechanism to show the reaction of 2‑bromo‑2‑methylpropane with OH–(aq).
Show the intermediate formed in this reaction.
Include all charges, partial charges, lone pairs and curly arrows as appropriate.
CH3
Br
C
H 3C
CH3
[3]
(ii)Name the mechanism for this reaction.
........................................................................................................................................ [1]
(d)
The original experiment is repeated at 25 °C with 2‑chloro‑2‑methylpropane instead of
2‑bromo‑2‑methylpropane. All other variables remain constant.
Predict the effect of using 2‑chloro‑2‑methylpropane compared to 2‑bromo‑2‑methylpropane
on the time taken for the pink colour to disappear. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 11]
9701/22/M/J/21
[Turn over
8
4
(a)
The table shows the structural formulae of four compounds, A, B, C and D, with molecular
formula C4H8.
(i)Complete the table by giving the systematic name of A, B, C and D.
structural formula
A
name
CH3CH2CH=CH2
H
H
C
B
C
H3C
CH3
H3C
H
C
C
H
C
CH3
D
CH2=C(CH3)2
[4]
(ii)Explain what is meant by stereoisomerism.
..............................................................................................................................................
........................................................................................................................................ [1]
(b)
W is an alkene with formula C4H8. It reacts with HBr to form two possible carbocations,
CH3C+(H)(CH2CH3) and H2C+CH2CH2CH3.
(i)Identify W as compound A, B, C or D.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/M/J/21
9
(ii)Draw the skeletal formula of the major organic product formed when HBr reacts with W.
Explain why this is the major organic product.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
[3]
(c)A sample of propan‑1‑ol reacts with concentrated sulfuric acid to form propene.
Identify the role of concentrated sulfuric acid in this reaction.
............................................................................................................................................... [1]
(d)Alcohol Y reacts completely when warmed with acidified Cr2O72– to form Z.
Z is distilled from the reaction mixture as soon as it is made.
Tollens’ reagent is added to a sample of Z and warmed. A silver mirror forms.
(i)Name the type of reaction that occurs when Y reacts to form Z.
........................................................................................................................................ [1]
(ii)Identify with a tick () the functional group(s) present in Z.
functional group
present in Z
aldehyde
ketone
carboxylic acid
[1]
© UCLES 2021
[Total: 12]
9701/22/M/J/21
[Turn over
10
5
S is a secondary alcohol with molecular formula C4H10O.
(a)Draw the displayed formula of S.
[1]
(b)
S is converted to V in a three‑step reaction sequence.
S
step 1
T
C4H10O
PBr3
C4H9Br
U
step 3
C4H9CN
dilute
acid
step 2
V
In step 1, the secondary alcohol S reacts with PBr3 to produce T, which has molecular formula
C4H9Br.
(i)Give the systematic name of T.
........................................................................................................................................ [1]
(ii)Name the type of reaction that occurs in step 1.
........................................................................................................................................ [1]
(iii)State the reagent(s) and conditions for step 2.
..............................................................................................................................................
........................................................................................................................................ [2]
(iv)Step 3 involves heating C4H9CN with dilute acid to form V.
Complete the equation for this reaction.
.....C4H9CN + .....H+ + .....H2O → ........................................
© UCLES 2021
9701/22/M/J/21
[2]
11
(v)An unlabelled sample contains either S, T or U.
The sample produces the infrared spectrum shown.
100
transmittance
/%
50
0
4000
3000
2000
1500
1000
500
wavenumber / cm–1
Explain how this spectrum confirms that the unknown sample contains U.
In your answer identify one relevant absorption in the infrared spectrum and the bond that
corresponds to this absorption in the region above 1500 cm–1.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 8]
9701/22/M/J/21
[Turn over
Cambridge International AS & A Level
*2129014836*
CHEMISTRY9701/41
Paper 4 A Level Structured Questions
May/June 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 24 pages. Any blank pages are indicated.
IB21 06_9701_41/5RP
© UCLES 2021
[Turn over
3
Answer all the questions in the spaces provided.
1
(a)The carbonates and hydroxides of Group 2 elements show similar trends in thermal stability.
Suggest and explain the variation in the trend in the thermal stability of the Group 2 hydroxides.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(b)Calcium hydroxide is slightly soluble in water.
(i)Write an equation to show the dissociation of calcium hydroxide, Ca(OH)2(s), in aqueous
solution. Include state symbols.
...............................................................
��������������������������������������������������������������� [1]
(ii)Calculate the solubility, in mol dm–3, of Ca(OH)2.
[Ksp: Ca(OH)2, 5.02 × 10–6 mol3 dm–9]
solubility = .............................. mol dm–3 [2]
(iii)Suggest how the solubility of Ca(OH)2 in aqueous NaOH compares to its solubility in
water.
Explain your reasoning.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 7]
9701/41/M/J/21
[Turn over
4
2
(a)Explain why chromium complexes are coloured.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(b) Four different compounds can be obtained when anhydrous chromium(III) chloride reacts with
water under various conditions. When samples of each compound are reacted separately with
aqueous silver nitrate, different amounts of silver chloride are precipitated. The precipitation
leaves the complex ions P, Q, R and S in solution.
formula of
compound
moles of AgCl precipitated
per mole of complex ion
complex ion
property of
complex ion
CrCl 3(H2O)6
3
P
non-polar
CrCl 3(H2O)5
2
Q
polar
CrCl 3(H2O)4
1
R
polar
CrCl 3(H2O)4
1
S
non-polar
(i)Draw three-dimensional diagrams for the structures of complex ions P, Q, R and S.
Include the charges for each complex ion.
P
Q
Cr
Cr
R
S
Cr
Cr
[4]
© UCLES 2021
9701/41/M/J/21
5
(ii)Suggest why complex ion S is non-polar.
..............................................................................................................................................
........................................................................................................................................ [1]
(c)The structure of picolinic acid is shown.
picolinic acid
CO2H
N
The conjugate base of picolinic acid is a bidentate ligand, Z.
(i)
Define the term bidentate ligand.
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw the structure of Z.
[1]
(iii)
Z reacts with aqueous chromium(III) ions, [Cr(H2O)6]3+, in a 3 : 1 ratio to form a new neutral
complex.
State the coordination number and the geometry of the chromium(III) centre in the
complex.
coordination number ......................................... geometry ����������������������������������������� [1]
(d)(NH4)2Cr2O7 decomposes readily on heating to form Cr2O3, steam and an inert colourless gas.
(i)Deduce the oxidation numbers of chromium in (NH4)2Cr2O7 and in Cr2O3.
(NH4)2Cr2O7 ................................................... Cr2O3 ��������������������������������������������������� [1]
(ii)Construct an equation for the thermal decomposition of (NH4)2Cr2O7.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 15]
9701/41/M/J/21
[Turn over
6
3
(a) (i)
Define the term transition element.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)State how the melting point and density of iron compare to those of calcium.
..............................................................................................................................................
........................................................................................................................................ [1]
(b) (i)
Define the term standard cell potential,
.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw a fully labelled diagram of the apparatus that can be used to measure the cell potential
of a cell composed of a Cu(II)/Cu electrode and an Fe(III)/Fe(II) electrode. Include all
necessary reactants.
[3]
© UCLES 2021
9701/41/M/J/21
7
(c)The reaction between S2O82–(aq) and I –(aq) is catalysed by adding a few drops of Fe3+(aq).
(i)Use equations to show the catalytic role of Fe3+ in this reaction.
[2]
(ii)Fe3+(aq) can oxidise I –(aq), whereas [Fe(CN)6]3–(aq) cannot oxidise I –(aq).
Use E o values to explain these observations.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(d)When aqueous solutions of S2O82– and tartrate ions are mixed the reaction proceeds very
slowly. However, this reaction proceeds quickly in the presence of an Fe3+(aq) catalyst.
The overall equation for this reaction is shown.
tartrate ions
OH
–
CO2–
O2C
+ 3S2O82– + 2H2O 2CO2 + 2HCO2– + 6H+ + 6SO42–
OH
(i)Suggest why this reaction is slow without the Fe3+ catalyst.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Use the overall equation to deduce the half-equation for the oxidation of tartrate ions,
C4H4O62–, to carbon dioxide, CO2, and methanoate ions, HCO2–.
C4H4O62– + .........................
© UCLES 2021
......................................................................
9701/41/M/J/21
[1]
[Turn over
8
(e) (i)Complete the following table to show the structures of the organic products formed when
tartaric acid reacts separately with each reagent. Identify each type of reaction.
tartaric acid
OH
CO2H
HO2C
OH
reagent
structure of organic product
type of reaction
an excess of LiAl H4
an excess of CH3COCl
[3]
(ii)Tartaric acid reacts with the amine 1-phenylethylamine, C6H5CH(NH2)CH3, to form an
ionic salt.
Draw the structure of the salt formed in this reaction. Include the charges on the ions.
[1]
© UCLES 2021
[Total: 17]
9701/41/M/J/21
9
4
(a)Samples of [Cu(H2O)6]2+ are reacted separately with an excess of aqueous sodium hydroxide
or with an excess of aqueous ammonia.
Give the following information about these reactions.
(i)reaction 1: [Cu(H2O)6]2+ with an excess of aqueous of sodium hydroxide
colour and state of the copper-containing species ..............................................................
ionic equation ......................................................................................................................
type of reaction ....................................................................................................................
[3]
(ii)reaction 2: [Cu(H2O)6]2+ with an excess of aqueous ammonia
colour and state of the copper-containing species ..............................................................
ionic equation ......................................................................................................................
type of reaction ....................................................................................................................
[3]
(b)Copper(I) oxide is added to hot dilute sulfuric acid. A blue solution, X, and a red-brown solid,
Y, form.
Suggest the identities of X and Y. Name the type of reaction.
X .................................................................................................................................................
Y .................................................................................................................................................
type of reaction ...........................................................................................................................
[2]
© UCLES 2021
[Total: 8]
9701/41/M/J/21
[Turn over
10
5
Dinitrogen pentoxide, N2O5, is dissolved in an inert solvent (solv) and the rate of decomposition
of N2O5 is investigated. This reaction produces nitrogen dioxide, which remains in solution, and
oxygen gas.
N2O5(solv) → 2NO2(solv) + 12 O2(g)
(a)Suggest what measurements could be used to follow the rate of this reaction from the given
information.
.....................................................................................................................................................
............................................................................................................................................... [1]
(b)In a separate experiment, the rate of the decomposition of N2O5(g) is investigated.
N2O5(g) → 2NO2(g) +
1
2 O2(g)
The graph shows the results obtained.
0.30
0.25
0.20
[N2O5]
0.15
/ mol dm–3
0.10
0.05
0
0
100
200
300
400
500
600
700
time / s
he reaction is first order with respect to N2O5. This can be confirmed from the graph using
T
half‑lives.
(i)Explain the term half-life of a reaction.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/41/M/J/21
11
(ii)Determine the half-life of this reaction. Show your working on the graph.
half-life = .............................. s [1]
(iii)
Suggest the effect on the half-life of this reaction if the initial concentration of N2O5 is
halved.
........................................................................................................................................ [1]
(c) (i)Use the graph in 5(b) to determine the rate of reaction at 200 s. Show your working.
rate = ..............................
units = ..............................
[2]
The rate equation for this reaction is shown.
rate = k [N2O5]
(ii)Use your answer to (c)(i) to calculate the value of the rate constant, k, for this reaction and
state its units.
k = .............................. units .............................. [1]
(d)Nitrogen dioxide reacts with ozone, O3, as shown.
2NO2 + O3 → N2O5 + O2
The rate equation for this reaction is rate = k [NO2][O3].
Suggest a possible two-step mechanism for this reaction.
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 9]
9701/41/M/J/21
[Turn over
12
6
(a)Compare and explain the relative acidities of butanoic acid, ethanol, ethanoic acid and water.
................................. > ................................. > ................................ > ................................
most acidic
least acidic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(b)
Three carboxylic acids, methanoic acid, HCO2H, ethanedioic acid, HO2CCO2H, and
butanedioic acid, HO2CCH2CH2CO2H, are compared. Two tests were carried out on separate
samples of each organic acid, as shown.
The following results were obtained.
test
reagents and
conditions
 = observed change
 = no observed reaction
HCO2H
HO2CCO2H
HO2CCH2CH2CO2H
1



2



observed change
(i)Complete the table with the reagents and conditions and the observed change for a
positive test.
Assume these organic acids all have a similar acid strength.
[3]
© UCLES 2021
9701/41/M/J/21
13
(ii)Each compound, HCO2H, HO2CCO2H and HO2CCH2CH2CO2H, is dissolved seperately in
CDCl 3. Proton (1H) NMR and carbon‑13 (13C) NMR spectra are then obtained.
Complete the table.
compound
number of peaks
in proton NMR
number of peaks
in carbon-13 NMR
HCO2H
HO2CCO2H
HO2CCH2CH2CO2H
[2]
(iii)The proton NMR spectrum of HCO2H in D2O is obtained.
escribe and explain the difference observed between this spectrum and the proton NMR
D
spectrum of HCO2H in (b)(ii).
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/41/M/J/21
[Turn over
14
(c)1,4-dibromobutane, Br(CH2)4Br, is used in the synthesis of the dicarboxylic acid J and diamine K
as shown.
BrCH2CH2CH2CH2Br
step 1
step 3
G
H
step 2
step 4
J
K
HO2CCH2CH2CO2H
H2NCH2CH2CH2CH2CH2CH2NH2
(i)Draw the structures of G and H in the boxes.
[2]
(ii)Suggest reagents and conditions for each of steps 1 to 4.
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
step 4 ...................................................................................................................................
[4]
© UCLES 2021
9701/41/M/J/21
15
(d)Polyamide L can be synthesised from dicarboxylic acid J, HO2C(CH2)2CO2H, and diamine K,
H2N(CH2)6NH2.
Draw the repeat unit of the polymer formed in the box. Any functional groups should be shown
displayed.
polyamide L
[2]
© UCLES 2021
[Total: 18]
9701/41/M/J/21
[Turn over
16
7
(a) 3-aminobenzoic acid can be synthesised from methylbenzene in three steps.
methylbenzene
M
N
step 1
step 2
step 3
3-aminobenzoic acid
CO2H
NH2
(i)Draw the structures of M and N in the boxes.
[2]
(ii)Suggest reagents and conditions for each step of the synthesis.
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
[3]
© UCLES 2021
9701/41/M/J/21
17
(b)A mixture of serine, HOCH2CH(NH2)CO2H, and lysine, H2N(CH2)4CH(NH2)CO2H, reacts to form
several different products.
(i)Draw the structures of the two structural isomers with the molecular formula C6H12N2O5
that could be present in the product mixture.
The functional group formed in each case should be displayed.
[3]
(ii)
redict the number of different structural isomers with the molecular formula C9H19N3O4
P
that could be present in the product mixture.
molecular formula
number of structural isomers formed
C9H19N3O4
[1]
© UCLES 2021
9701/41/M/J/21
[Turn over
18
(c)Glutathione is a naturally occurring compound found in plants.
glutathione
O
SH
O
N
N
HO
NH2
H
H
O
OH
O
(i)On the diagram of glutathione, label each chiral centre with an asterisk (*).
[1]
(ii)
Draw the structures of the three products formed after complete acid hydrolysis of
glutathione. Assume the thiol group, –SH, does not react.
[2]
(iii)Glutathione is soluble in water.
By referring to the structure of glutathione, explain why glutathione is soluble in water.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 13]
9701/41/M/J/21
19
8
(a)The sketch graph for the titration of ethanoic acid, CH3CO2H, with sodium hydroxide is shown.
14
12
10
pH
8
equivalence point
6
4
2
0
volume of sodium hydroxide / cm3
(i)In the region circled on the graph, identify the two organic species that are present in
the solution. Explain why the pH of the mixture only changes slowly and gradually in this
region when sodium hydroxide is being added.
two species present ...............................................
...............................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [3]
(ii)The equivalence point in this acid-base titration is where the two solutions have been
mixed in exactly equal molar proportion.
Suggest why the pH is greater than 7 at the equivalence point in this titration.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/41/M/J/21
[Turn over
20
(b)An impure sample of ammonium vanadate(V), NH4VO3, with mass 0.150 g, is dissolved in an
excess of dilute acid.
In this solution all vanadium is present as VO2+ ions. An excess of zinc powder is added to the
solution and all the VO2+ ions are reduced to V2+ ions. The mixture is filtered to remove any
remaining zinc powder.
VO2+ + 4H+ + 3e– → V2+ + 2H2O
When the resulting solution is titrated, 20.10 cm3 of 0.0250 mol dm–3 acidified MnO4– oxidises all
V2+ ions back to VO2+ ions.
MnO4– + 8H+ + 5e–
Mn2+ + 4H2O
Calculate the percentage by mass of NH4VO3 in the 0.150 g impure sample of NH4VO3.
Give your answer to three significant figures.
[Mr: NH4VO3, 116.9]
percentage by mass of NH4VO3 = .............................. % [3]
[Total: 7]
© UCLES 2021
9701/41/M/J/21
21
9The carbon-13 (13C) NMR spectrum of compound A, C8H8O2, contains six peaks.
Compound A reacts with an excess of bromine water to give compound B, C8H6Br2O2.
Compound A reacts with alkaline aqueous iodine to form a yellow precipitate C and compound D.
Compound D reacts with PCl 5 to form compound E, C7H5O2Cl.
Compound E reacts with propan-2-ol to form compound F.
Draw the structures of compounds A, B, C, D, E and F in the boxes.
A C8H8O2
C yellow ppt.
alkaline I2(aq)
D
+
Br2(aq)
PCl 5
B C8H6Br2O2
E C7H5O2Cl
propan-2-ol
F
[6]
© UCLES 2021
9701/41/M/J/21
[Turn over
Cambridge International AS & A Level
*2165639790*
CHEMISTRY9701/42
Paper 4 A Level Structured Questions
May/June 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 24 pages. Any blank pages are indicated.
IB21 06_9701_42/3RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1
(a)An aqueous solution of chromium(III) contains the green [Cr(H2O)6]3+ complex ion.
(i)
Complete the electronic configuration of an isolated, gaseous Cr3+ ion.
1s2 ��������������������������������������������������������������������������������������������������������������������������������� [1]
(ii)
Define the term complex ion.
..............................................................................................................................................
........................................................................................................................................ [1]
(b)[Cr(H2O)6]3+(aq) shows some similar chemical properties to [Co(H2O)6]2+(aq).
Samples of [Cr(H2O)6]3+ are reacted separately with either NaOH(aq), H2O2(aq), or excess
NH3(aq).
Use this information and the Data Booklet to suggest the formula of the chromium species
formed. State the type of reaction taking place in each case.
reagent added to
[Cr(H2O)6]3+(aq)
formula of chromium
species formed
type of reaction
NaOH(aq)
H2O2(aq)
an excess of NH3(aq)
[5]
(c)[Cr(H2O)6]2+ and [Cr2(O2CCH3)4(H2O)2] are both complexes of chromium(II) and have different
colours.
Explain why the colours of these complexes are different.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
9701/42/M/J/21
3
(d)The structure of [Cr2(O2CCH3)4(H2O)2] is shown. Ethanoate ions act as ligands in this complex.
The ethanoate ligand, CH3CO2–, is shown as O
O.
O
O
O
H 2O
Cr
O
Cr
OH2
O
O
(i)
O
O
Water and ethanoate ions behave as different types of ligand in this complex.
Suggest an explanation for this statement.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Deduce the coordination number of Cr and the geometry around each Cr atom in this
structure.
coordination number ............................................................................................................
geometry around Cr atom ���������������������������������������������������������������������������������������������������
[1]
(iii)State the type of bond between the two atoms in the Cr–Cr bond.
........................................................................................................................................ [1]
(e)The [Cr2(O2CCH3)4(H2O)2] complex reacts with aqueous acid to form Cr2+(aq) ions.
Cr2+(aq) ions react with O2(aq) under acidic conditions. Cr3+(aq) ions are formed.
Use the Data Booklet to answer the following questions.
(i)Construct an ionic equation for the reaction of Cr2+(aq) with O2(aq) under acidic conditions.
........................................................................................................................................ [2]
(ii)Calculate
for the reaction in (e)(i).
= .............................. V [1]
[Total: 15]
© UCLES 2021
9701/42/M/J/21
[Turn over
4
2
(a)State and explain the trend observed in the thermal stability of the Group 2 nitrates.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(b) (i)Lead(II) nitrate, Pb(NO3)2, decomposes on heating in a similar manner to the Group 2
nitrates.
Write an equation for the decomposition of lead(II) nitrate.
........................................................................................................................................ [1]
(ii)
uggest how the ease of decomposition of Pb(NO3)2 would compare to that of Ba(NO3)2.
S
Explain your answer. You may find it useful to refer to the Data Booklet.
..............................................................................................................................................
........................................................................................................................................ [1]
(c) (i)
arium ethanedioate, BaC2O4, decomposes on heating to produce barium oxide and a
B
mixture of two different gases.
Construct an equation for the decomposition of barium ethanedioate.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/M/J/21
5
(ii)An impure sample of BaC2O4, of mass 0.500 g, is added to 50.0 cm3 of 0.0200 mol dm–3
acidified MnO4–(aq), an excess. A redox reaction takes place and all the BaC2O4 reacts.
he resulting solution, containing unreacted acidified MnO4–, is titrated with 0.0500 mol dm–3
T
Fe2+(aq).
The end-point is reached when 30.40 cm3 of 0.0500 mol dm–3 Fe2+(aq) has been added.
C2O42–
2CO2 + 2e–
MnO4– + 8H+ + 5e–
Fe2+
Mn2+ + 4H2O
Fe3+ + e–
Calculate the percentage by mass of BaC2O4 in the 0.500 g impure sample. Show your
working.
[Mr: BaC2O4, 225.3]
percentage by mass of BaC2O4 = .............................. [4]
(d) Barium hydroxide, Ba(OH)2, is completely dissociated in aqueous solution.
Calculate the pH of 0.120 mol dm–3 Ba(OH)2(aq) at 298 K.
pH = .............................. [2]
[Total: 12]
© UCLES 2021
9701/42/M/J/21
[Turn over
6
3
(a) (i)
Define the term standard electrode potential.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
hree redox systems, A, B and C, are shown. The ligand 1,2-diaminoethane, H2NCH2CH2NH2,
T
is represented by en.
A
[Ru(H2O)6]3+ + e–
[Ru(H2O)6]2+
B
[Ru(NH3)6]3+ + e–
[Ru(NH3)6]2+
C
[Ru(en)3]3+ + e–
[Ru(en)3]2+
wo electrochemical cells are set up to compare the standard electrode potentials, E o, of three
T
half-cells. The diagrams show the relative potential of each electrode.
+
–
V
+
salt bridge
Pt
[Ru(en)3]3+
[Ru(en)3]2+
–
V
salt bridge
Pt
Pt
[Ru(NH3)6]3+
[Ru(NH3)6]2+
[Ru(H2O)6]3+
[Ru(H2O)6]2+
Pt
[Ru(en)3]3+
[Ru(en)3]2+
(ii)Use this information to complete the table by adding the labels A, B and C to deduce the
order of E o for the three half-cells.
redox system
Eo
most negative
least negative
[1]
© UCLES 2021
9701/42/M/J/21
7
(iii)The complex [Ru(en)3]3+ shows stereoisomerism. The ligand en is bidentate.
Draw three-dimensional diagrams to show the two isomers of [Ru(en)3]3+. Represent the
ligand en by using
N
N
.
Name the type of stereoisomerism.
isomer 1
isomer 2
Ru
Ru
type of stereoisomerism ......................................................................................................
[3]
(b) (i)An electrochemical cell consists of a Br2/Br – half-cell and a Ag+/Ag half-cell, under standard
conditions.
. Deduce the direction of electron flow in the wire
Use the Data Booklet to calculate the
through the voltmeter between these two half-cells.
= .............................. V
direction of electron flow from ....................................... to ����������������������������������������� [1]
(ii)Water is added to the Ag+/Ag half-cell in (b)(i).
Suggest the effect of this addition on the Ecell. Place a tick ( ) in the appropriate box.
less positive
no change
more positive
Explain your answer.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/42/M/J/21
[Turn over
8
(c) S
ilver bromide, AgBr, dissolves in an aqueous solution of S2O32– ions to form the complex ion
[Ag(S2O3)2]3–. The S2O32– ions act as monodentate ligands.
equilibrium 1
(i)
AgBr(s) + 2S2O32–(aq)
[Ag(S2O3)2]3–(aq) + Br –(aq)
Define the term ligand.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Write an expression for the equilibrium constant, Kc, for equilibrium 1.
Kc =
[1]
(iii)Some additional data are given about the dissolution of AgBr in S2O32–(aq).
equilibrium constant
numerical value
solubility product, Ksp, of AgBr
5.4 × 10–13
stability constant, Kstab, of [Ag(S2O3)2]3–
2.9 × 1013
Use your answer to (c)(ii) and these data to calculate Kc for equilibrium 1. Include the units
for Kc.
Kc = .............................. units .............................. [2]
(d) The numerical values for the stability constants, Kstab, of two other silver(I) complexes are
given.
silver(I) complex
numerical value of Kstab
[Ag(CN)2]–
5.3 × 1018
[Ag(NH3)2]+
1.6 × 107
An aqueous solution containing Ag+ is added to a solution containing equal concentrations of
CN–(aq), NH3(aq) and S2O32–(aq). The mixture is left to reach equilibrium.
Deduce the relative concentrations of [Ag(CN)2]–, [Ag(NH3)2]+ and [Ag(S2O3)2]3– present in the
resulting mixture. Explain your answer.
................................. > ................................. > ................................
highest concentration
lowest concentration
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 15]
9701/42/M/J/21
9
4
(a) (i)
Define the term lattice energy.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)
Use the following data to calculate a value for the enthalpy change of solution of
copper(II) chloride, CuCl 2(s). You might find it helpful to construct an energy cycle.
enthalpy change of hydration of Cl – = –378 kJ mol–1
enthalpy change of hydration of Cu2+ = –2099 kJ mol–1
lattice energy of CuCl 2(s)
= –2824 kJ mol–1
enthalpy change of solution of CuCl 2(s) = .............................. kJ mol–1 [2]
(iii)The enthalpy change of hydration of Ca2+ is –1579 kJ mol–1.
Use the Data Booklet to suggest why there is a big difference in the values of ∆Hhyd for Ca2+
and Cu2+.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(b) (i)Identify the substances formed at the anode and at the cathode during the electrolysis of
saturated CaCl 2(aq).
at the anode .........................................................................................................................
at the cathode ......................................................................................................................
[1]
(ii)
Calcium can be produced by the electrolysis of molten calcium chloride, CaCl 2(l).
alculate the mass, in g, of Ca formed when a current of 0.75 A passes through CaCl 2(l)
C
for 60 minutes.
[Ar: Ca, 40.1]
© UCLES 2021
mass of Ca = .............................. g [2]
9701/42/M/J/21
[Turn over
10
(c) (i)Explain what is meant by the term entropy of a system.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Place one tick ( ) in each row of the table to show the sign of each entropy change, ∆S.
process
∆S is negative
∆S is zero
∆S is positive
NaCl dissolving in water
water solidifying to ice
[1]
(iii)
he evaporation of one mole of water has a standard Gibbs free energy change, ∆G o, of
T
+8.6 kJ at 25 °C.
Sketch a graph on the axes to show how ∆G o changes for this process between 25 °C and
150 °C at 101 kPa.
positive
G o
0
25
50
temperature / C
75 100 125 150
negative
[2]
(d)The reaction between A and B is feasible at low temperatures but is not feasible at high
temperatures.
A + B
C + D
Deduce the signs of ∆H and ∆S for this reaction and explain why the feasibility changes with
temperature.
sign of ∆H = .............................. sign of ∆S = ..............................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 15]
9701/42/M/J/21
11
5
(a) Describe and explain the relative basicities of phenylamine, ethylamine and 4-nitrophenylamine.
................................. > ................................. > ................................
most basic
least basic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(b)The dye R can be synthesised from 4-nitrophenylamine in two steps.
Q
4-nitrophenylamine
O2N
NH2
step 1
step 2
R
OH
O2N
N
N
(i)Deduce and draw the structure of the organic salt Q in the box.
[1]
(ii)Suggest reagents and conditions for step 1 and 2 in (b).
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
[2]
© UCLES 2021
9701/42/M/J/21
[Turn over
12
(c)Compound G can be synthesised from methylbenzene in three steps.
E
F
CH3
step 1
step 2
step 3
G
CO2H
NO2
Br
(i)Give the systematic name of compound G.
........................................................................................................................................ [1]
(ii)Deduce the identities of E and F and draw their structures in the boxes.
[2]
(iii)Suggest reagents and conditions for each of steps 1 to 3 in (c).
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
[3]
© UCLES 2021
[Total: 13]
9701/42/M/J/21
13
6
(a)There are four possible structural isomers of C8H10 that contain a benzene ring.
Draw the skeletal formulae of the four structural isomers in the appropriate boxes. The number
of peaks observed in the carbon‑13 (13C) NMR spectrum of each compound is given.
isomer 1
isomer 2
three peaks in 13C NMR
four peaks in 13C NMR
isomer 3
isomer 4
five peaks in 13C NMR
six peaks in 13C NMR
[4]
© UCLES 2021
9701/42/M/J/21
[Turn over
14
(b)A three-step synthesis of X (C10H10O) from benzene is suggested as shown.
W
Cl (CH2)3CO2H
Al Cl 3
step 1
step 2
Cl
O
step 3
Al Cl 3
X (C10H10O)
(i)Step 1 is the alkylation of benzene by electrophilic substitution.
Use R–Cl to represent Cl (CH2)3CO2H.
Write an equation for the formation of an electrophile from R–Cl and Al Cl 3.
........................................................................................................................................ [1]
(ii)Deduce and draw the structures of W and X in the boxes.
[2]
(iii)Suggest the reagents and conditions for step 2.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/M/J/21
15
(iv)
Complete the mechanism for the reaction of benzene with the electrophile formed
in (b)(i).
Include all relevant charges and curly arrows showing the movement of electron pairs.
Draw the structure of the intermediate.
intermediate
R
[3]
© UCLES 2021
[Total: 11]
9701/42/M/J/21
[Turn over
16
7
(a) In aqueous solution, chlorine dioxide, Cl O2, reacts with hydroxide ions as shown.
2Cl O2 + 2OH– → Cl O3– + Cl O2– + H2O
series of experiments is carried out using different concentrations of Cl O2 and OH–. The
A
table shows the results obtained.
experiment
[Cl O2]
/ mol dm–3
[OH–]
/ mol dm–3
initial rate
/ mol dm–3 min–1
1
0.020
0.030
7.20 × 10–4
2
0.020
0.120
2.88 × 10–3
3
0.050
0.030
4.50 × 10–3
(i)Explain the term order of reaction.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Use the data in the table to determine the order of reaction with respect to each reactant,
Cl O2 and OH–.
Explain your reasoning.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)Use your answer to (a)(ii) to construct the rate equation for this reaction.
rate = ............................................................................................................................. [1]
(iv)
se your rate equation and the data from experiment 1 to calculate the rate constant, k,
U
for this reaction.
Include the units of k.
k = .............................. units .............................. [2]
© UCLES 2021
9701/42/M/J/21
17
Question 7 continues on the next page.
© UCLES 2021
9701/42/M/J/21
[Turn over
18
(b) The decomposition of benzenediazonium ions, C6H5N2+, using a large excess of water, is a
first‑order reaction.
The graph shows the results obtained.
0.025
0.020
0.015
[C6H5N2 ]
/ mol dm–3
+
0.010
0.005
0
0
100
200
300
400
500
600
time / s
(i)Draw the structure of the organic product formed in this reaction.
[1]
(ii)
Use the graph to determine the rate of reaction at 100 s. Show your working.
rate = .............................. mol dm–3 s–1 [1]
© UCLES 2021
9701/42/M/J/21
19
(c)Sketch a concentration–time graph for a zero-order reaction.
Use your graph to suggest how successive half-lives for a zero-order reaction vary as the
concentration of a reactant decreases. Indicate this by placing a tick ( ) in the appropriate box
in the table.
concentration
time
successive half-lives
decrease
no change in
successive half-lives
successive half-lives
increase
[1]
© UCLES 2021
[Total: 9]
9701/42/M/J/21
[Turn over
20
8
(a) S
tate and explain the relative rate of hydrolysis of acyl chlorides, alkyl chlorides and
aryl chlorides.
................................. > ................................. > ................................
fastest
slowest
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
© UCLES 2021
9701/42/M/J/21
21
(b)The drug remifentanil is shown.
remifentanil
O
O
O
O
N
N
O
Remifentanil is completely hydrolysed under acidic conditions. Three different organic
compounds are formed.
Draw the structures for these organic compounds in the boxes.
[3]
© UCLES 2021
9701/42/M/J/21
[Turn over
22
(c)Compound Y, C5H10O2, reacts with Na2CO3(aq) to evolve bubbles of gas. The proton (1H) NMR
spectrum of compound Y in D2O is shown.
2
/ ppm
1
0
(i)Use this information to suggest a structure for Y.
[1]
(ii)Use the Data Booklet, the proton (1H) NMR spectrum and your answer to (c)(i) to complete
the table.
chemical
shift (δ)
environment of proton
splitting pattern
number of 1H atoms
responsible for the peak
0.95
1.90
2.20
[3]
© UCLES 2021
[Total: 10]
9701/42/M/J/21
Cambridge International AS & A Level
*4044835856*
CHEMISTRY9701/43
Paper 4 A Level Structured Questions
May/June 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 24 pages. Any blank pages are indicated.
IB21 06_9701_43/FP
© UCLES 2021
[Turn over
3
Answer all the questions in the spaces provided.
1
(a)The carbonates and hydroxides of Group 2 elements show similar trends in thermal stability.
Suggest and explain the variation in the trend in the thermal stability of the Group 2 hydroxides.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(b)Calcium hydroxide is slightly soluble in water.
(i)Write an equation to show the dissociation of calcium hydroxide, Ca(OH)2(s), in aqueous
solution. Include state symbols.
...............................................................
��������������������������������������������������������������� [1]
(ii)Calculate the solubility, in mol dm–3, of Ca(OH)2.
[Ksp: Ca(OH)2, 5.02 × 10–6 mol3 dm–9]
solubility = .............................. mol dm–3 [2]
(iii)Suggest how the solubility of Ca(OH)2 in aqueous NaOH compares to its solubility in
water.
Explain your reasoning.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 7]
9701/43/M/J/21
[Turn over
4
2
(a)Explain why chromium complexes are coloured.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(b) Four different compounds can be obtained when anhydrous chromium(III) chloride reacts with
water under various conditions. When samples of each compound are reacted separately with
aqueous silver nitrate, different amounts of silver chloride are precipitated. The precipitation
leaves the complex ions P, Q, R and S in solution.
formula of
compound
moles of AgCl precipitated
per mole of complex ion
complex ion
property of
complex ion
CrCl 3(H2O)6
3
P
non-polar
CrCl 3(H2O)5
2
Q
polar
CrCl 3(H2O)4
1
R
polar
CrCl 3(H2O)4
1
S
non-polar
(i)Draw three-dimensional diagrams for the structures of complex ions P, Q, R and S.
Include the charges for each complex ion.
P
Q
Cr
Cr
R
S
Cr
Cr
[4]
© UCLES 2021
9701/43/M/J/21
5
(ii)Suggest why complex ion S is non-polar.
..............................................................................................................................................
........................................................................................................................................ [1]
(c)The structure of picolinic acid is shown.
picolinic acid
CO2H
N
The conjugate base of picolinic acid is a bidentate ligand, Z.
(i)
Define the term bidentate ligand.
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw the structure of Z.
[1]
(iii)
Z reacts with aqueous chromium(III) ions, [Cr(H2O)6]3+, in a 3 : 1 ratio to form a new neutral
complex.
State the coordination number and the geometry of the chromium(III) centre in the
complex.
coordination number ......................................... geometry ����������������������������������������� [1]
(d)(NH4)2Cr2O7 decomposes readily on heating to form Cr2O3, steam and an inert colourless gas.
(i)Deduce the oxidation numbers of chromium in (NH4)2Cr2O7 and in Cr2O3.
(NH4)2Cr2O7 ................................................... Cr2O3 ��������������������������������������������������� [1]
(ii)Construct an equation for the thermal decomposition of (NH4)2Cr2O7.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 15]
9701/43/M/J/21
[Turn over
6
3
(a) (i)
Define the term transition element.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)State how the melting point and density of iron compare to those of calcium.
..............................................................................................................................................
........................................................................................................................................ [1]
(b) (i)
Define the term standard cell potential,
.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw a fully labelled diagram of the apparatus that can be used to measure the cell potential
of a cell composed of a Cu(II)/Cu electrode and an Fe(III)/Fe(II) electrode. Include all
necessary reactants.
[3]
© UCLES 2021
9701/43/M/J/21
7
(c)The reaction between S2O82–(aq) and I –(aq) is catalysed by adding a few drops of Fe3+(aq).
(i)Use equations to show the catalytic role of Fe3+ in this reaction.
[2]
(ii)Fe3+(aq) can oxidise I –(aq), whereas [Fe(CN)6]3–(aq) cannot oxidise I –(aq).
Use E o values to explain these observations.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(d)When aqueous solutions of S2O82– and tartrate ions are mixed the reaction proceeds very
slowly. However, this reaction proceeds quickly in the presence of an Fe3+(aq) catalyst.
The overall equation for this reaction is shown.
tartrate ions
OH
–
CO2–
O2C
+ 3S2O82– + 2H2O 2CO2 + 2HCO2– + 6H+ + 6SO42–
OH
(i)Suggest why this reaction is slow without the Fe3+ catalyst.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Use the overall equation to deduce the half-equation for the oxidation of tartrate ions,
C4H4O62–, to carbon dioxide, CO2, and methanoate ions, HCO2–.
C4H4O62– + .........................
© UCLES 2021
......................................................................
9701/43/M/J/21
[1]
[Turn over
8
(e) (i)Complete the following table to show the structures of the organic products formed when
tartaric acid reacts separately with each reagent. Identify each type of reaction.
tartaric acid
OH
CO2H
HO2C
OH
reagent
structure of organic product
type of reaction
an excess of LiAl H4
an excess of CH3COCl
[3]
(ii)Tartaric acid reacts with the amine 1-phenylethylamine, C6H5CH(NH2)CH3, to form an
ionic salt.
Draw the structure of the salt formed in this reaction. Include the charges on the ions.
[1]
© UCLES 2021
[Total: 17]
9701/43/M/J/21
9
4
(a)Samples of [Cu(H2O)6]2+ are reacted separately with an excess of aqueous sodium hydroxide
or with an excess of aqueous ammonia.
Give the following information about these reactions.
(i)reaction 1: [Cu(H2O)6]2+ with an excess of aqueous of sodium hydroxide
colour and state of the copper-containing species ..............................................................
ionic equation ......................................................................................................................
type of reaction ....................................................................................................................
[3]
(ii)reaction 2: [Cu(H2O)6]2+ with an excess of aqueous ammonia
colour and state of the copper-containing species ..............................................................
ionic equation ......................................................................................................................
type of reaction ....................................................................................................................
[3]
(b)Copper(I) oxide is added to hot dilute sulfuric acid. A blue solution, X, and a red-brown solid,
Y, form.
Suggest the identities of X and Y. Name the type of reaction.
X .................................................................................................................................................
Y .................................................................................................................................................
type of reaction ...........................................................................................................................
[2]
© UCLES 2021
[Total: 8]
9701/43/M/J/21
[Turn over
10
5
Dinitrogen pentoxide, N2O5, is dissolved in an inert solvent (solv) and the rate of decomposition
of N2O5 is investigated. This reaction produces nitrogen dioxide, which remains in solution, and
oxygen gas.
N2O5(solv) → 2NO2(solv) + 12 O2(g)
(a)Suggest what measurements could be used to follow the rate of this reaction from the given
information.
.....................................................................................................................................................
............................................................................................................................................... [1]
(b)In a separate experiment, the rate of the decomposition of N2O5(g) is investigated.
N2O5(g) → 2NO2(g) +
1
2 O2(g)
The graph shows the results obtained.
0.30
0.25
0.20
[N2O5]
0.15
/ mol dm–3
0.10
0.05
0
0
100
200
300
400
500
600
700
time / s
he reaction is first order with respect to N2O5. This can be confirmed from the graph using
T
half‑lives.
(i)Explain the term half-life of a reaction.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/43/M/J/21
11
(ii)Determine the half-life of this reaction. Show your working on the graph.
half-life = .............................. s [1]
(iii)
Suggest the effect on the half-life of this reaction if the initial concentration of N2O5 is
halved.
........................................................................................................................................ [1]
(c) (i)Use the graph in 5(b) to determine the rate of reaction at 200 s. Show your working.
rate = ..............................
units = ..............................
[2]
The rate equation for this reaction is shown.
rate = k [N2O5]
(ii)Use your answer to (c)(i) to calculate the value of the rate constant, k, for this reaction and
state its units.
k = .............................. units .............................. [1]
(d)Nitrogen dioxide reacts with ozone, O3, as shown.
2NO2 + O3 → N2O5 + O2
The rate equation for this reaction is rate = k [NO2][O3].
Suggest a possible two-step mechanism for this reaction.
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 9]
9701/43/M/J/21
[Turn over
12
6
(a)Compare and explain the relative acidities of butanoic acid, ethanol, ethanoic acid and water.
................................. > ................................. > ................................ > ................................
most acidic
least acidic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(b)
Three carboxylic acids, methanoic acid, HCO2H, ethanedioic acid, HO2CCO2H, and
butanedioic acid, HO2CCH2CH2CO2H, are compared. Two tests were carried out on separate
samples of each organic acid, as shown.
The following results were obtained.
test
reagents and
conditions
 = observed change
 = no observed reaction
HCO2H
HO2CCO2H
HO2CCH2CH2CO2H
1



2



observed change
(i)Complete the table with the reagents and conditions and the observed change for a
positive test.
Assume these organic acids all have a similar acid strength.
[3]
© UCLES 2021
9701/43/M/J/21
13
(ii)Each compound, HCO2H, HO2CCO2H and HO2CCH2CH2CO2H, is dissolved seperately in
CDCl 3. Proton (1H) NMR and carbon‑13 (13C) NMR spectra are then obtained.
Complete the table.
compound
number of peaks
in proton NMR
number of peaks
in carbon-13 NMR
HCO2H
HO2CCO2H
HO2CCH2CH2CO2H
[2]
(iii)The proton NMR spectrum of HCO2H in D2O is obtained.
escribe and explain the difference observed between this spectrum and the proton NMR
D
spectrum of HCO2H in (b)(ii).
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/43/M/J/21
[Turn over
14
(c)1,4-dibromobutane, Br(CH2)4Br, is used in the synthesis of the dicarboxylic acid J and diamine K
as shown.
BrCH2CH2CH2CH2Br
step 1
step 3
G
H
step 2
step 4
J
K
HO2CCH2CH2CO2H
H2NCH2CH2CH2CH2CH2CH2NH2
(i)Draw the structures of G and H in the boxes.
[2]
(ii)Suggest reagents and conditions for each of steps 1 to 4.
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
step 4 ...................................................................................................................................
[4]
© UCLES 2021
9701/43/M/J/21
15
(d)Polyamide L can be synthesised from dicarboxylic acid J, HO2C(CH2)2CO2H, and diamine K,
H2N(CH2)6NH2.
Draw the repeat unit of the polymer formed in the box. Any functional groups should be shown
displayed.
polyamide L
[2]
© UCLES 2021
[Total: 18]
9701/43/M/J/21
[Turn over
16
7
(a) 3-aminobenzoic acid can be synthesised from methylbenzene in three steps.
methylbenzene
M
N
step 1
step 2
step 3
3-aminobenzoic acid
CO2H
NH2
(i)Draw the structures of M and N in the boxes.
[2]
(ii)Suggest reagents and conditions for each step of the synthesis.
step 1 ...................................................................................................................................
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
[3]
© UCLES 2021
9701/43/M/J/21
17
(b)A mixture of serine, HOCH2CH(NH2)CO2H, and lysine, H2N(CH2)4CH(NH2)CO2H, reacts to form
several different products.
(i)Draw the structures of the two structural isomers with the molecular formula C6H12N2O5
that could be present in the product mixture.
The functional group formed in each case should be displayed.
[3]
(ii)
redict the number of different structural isomers with the molecular formula C9H19N3O4
P
that could be present in the product mixture.
molecular formula
number of structural isomers formed
C9H19N3O4
[1]
© UCLES 2021
9701/43/M/J/21
[Turn over
18
(c)Glutathione is a naturally occurring compound found in plants.
glutathione
O
SH
O
N
N
HO
NH2
H
H
O
OH
O
(i)On the diagram of glutathione, label each chiral centre with an asterisk (*).
[1]
(ii)
Draw the structures of the three products formed after complete acid hydrolysis of
glutathione. Assume the thiol group, –SH, does not react.
[2]
(iii)Glutathione is soluble in water.
By referring to the structure of glutathione, explain why glutathione is soluble in water.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 13]
9701/43/M/J/21
19
8
(a)The sketch graph for the titration of ethanoic acid, CH3CO2H, with sodium hydroxide is shown.
14
12
10
pH
8
equivalence point
6
4
2
0
volume of sodium hydroxide / cm3
(i)In the region circled on the graph, identify the two organic species that are present in
the solution. Explain why the pH of the mixture only changes slowly and gradually in this
region when sodium hydroxide is being added.
two species present ...............................................
...............................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [3]
(ii)The equivalence point in this acid-base titration is where the two solutions have been
mixed in exactly equal molar proportion.
Suggest why the pH is greater than 7 at the equivalence point in this titration.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/43/M/J/21
[Turn over
20
(b)An impure sample of ammonium vanadate(V), NH4VO3, with mass 0.150 g, is dissolved in an
excess of dilute acid.
In this solution all vanadium is present as VO2+ ions. An excess of zinc powder is added to the
solution and all the VO2+ ions are reduced to V2+ ions. The mixture is filtered to remove any
remaining zinc powder.
VO2+ + 4H+ + 3e– → V2+ + 2H2O
When the resulting solution is titrated, 20.10 cm3 of 0.0250 mol dm–3 acidified MnO4– oxidises all
V2+ ions back to VO2+ ions.
MnO4– + 8H+ + 5e–
Mn2+ + 4H2O
Calculate the percentage by mass of NH4VO3 in the 0.150 g impure sample of NH4VO3.
Give your answer to three significant figures.
[Mr: NH4VO3, 116.9]
percentage by mass of NH4VO3 = .............................. % [3]
[Total: 7]
© UCLES 2021
9701/43/M/J/21
21
9The carbon-13 (13C) NMR spectrum of compound A, C8H8O2, contains six peaks.
Compound A reacts with an excess of bromine water to give compound B, C8H6Br2O2.
Compound A reacts with alkaline aqueous iodine to form a yellow precipitate C and compound D.
Compound D reacts with PCl 5 to form compound E, C7H5O2Cl.
Compound E reacts with propan-2-ol to form compound F.
Draw the structures of compounds A, B, C, D, E and F in the boxes.
A C8H8O2
C yellow ppt.
alkaline I2(aq)
D
+
Br2(aq)
PCl 5
B C8H6Br2O2
E C7H5O2Cl
propan-2-ol
F
[6]
© UCLES 2021
9701/43/M/J/21
[Turn over
Cambridge International AS & A Level
CHEMISTRY
9701/11
Paper 1 Multiple Choice
October/November 2021
1 hour
You must answer on the multiple choice answer sheet.
*2315248955*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 11_9701_11/FP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
The mass spectrum of a sample of neon is shown. The relative abundance of each peak is
written in brackets above it.
(100)
relative
abundance
(8)
(0.3)
20
21
22
mass
charge
What is the relative atomic mass, Ar, of this sample of neon?
A
2
20.15
B
20.20
C
21.00
D
21.82
2.0 g of ammonium nitrate, NH4NO3, decomposes to give 0.90 g of water and a single gas.
What is the identity of the gas?
A
3
B
NO2
C
N2O
D
N2
Which of these elements has the highest fifth ionisation energy?
A
4
NO
C
B
N
C
P
D
The ion X2+ has the same electronic configuration as the atom Kr.
What is the electronic configuration of an atom of X?
A
[Ar] 4s23d104p6
B
[Ar] 4s23d104p65s2
C
[Ar] 4s24d104p6
D
[Ar] 4s24d104p65s2
© UCLES 2021
9701/11/O/N/21
Si
3
5
6
Which type of interaction exists between water molecules and metal cations in aqueous solution?
A
dipole-dipole interactions
B
hydrogen bonds
C
ion-dipole interactions
D
ionic bonds
Which substance shows the greatest deviation from the properties of an ideal gas under room
conditions?
A
7
CO2(g)
B
H2(g)
C
Ne(g)
D
NH3(g)
In order to determine the enthalpy of neutralisation of a strong acid and a strong alkali, 25.0 cm3
of 2.00 mol dm‒3 sodium hydroxide is added to 25.0 cm3 of 2.00 mol dm‒3 hydrochloric acid. The
increase in temperature is 12 C.
In a second experiment, the same method is used, but 50.0 cm3 of 2.00 mol dm‒3
sodium hydroxide is added to 50.0 cm3 of 2.00 mol dm‒3 hydrochloric acid.
What is the increase in temperature in the second experiment?
A
8
9
6 C
B
12 C
C
24 C
D
48 C
Which equation represents the enthalpy change of atomisation of iodine?
A
1
I (g)
2 2
 I(g)
B
I2(g)  2I(g)
C
1
I (s)
2 2
D
I2(s)  2I(g)
 I(g)
Zinc atoms can be oxidised to Zn2+ ions by dichromate(VI) ions in acid solution. Chromium is
reduced to Cr3+ in this reaction.
Which equation is correct?
A
Cr2O72– + Zn + 14H+  2Cr3+ + Zn2+ + 7H2O
B
Cr2O72– + Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
C
Cr2O72– + 3Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
D
2Cr2O72– + 3Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
© UCLES 2021
9701/11/O/N/21
[Turn over
4
10 The equation shows that H2(g) and I2(g) react to form an equilibrium mixture.
H2(g) + I2(g)
H o = –9.6 kJ mol–1
2HI(g)
A mixture containing equal amounts of H2(g) and I2(g) is made at temperature T1 and the
composition of the mixture is monitored. A graph of the results is shown.
0.5
mole fraction
of I2(g)
0.23
0
time
0
The experiment is repeated at a lower temperature, T2.
Which new graph would be obtained?
A
B
0.5
0.5
mole fraction
of I2(g)
mole fraction
of I2(g)
0.23
0.23
0
0
0
time
0
C
D
0.5
0.5
mole fraction
of I2(g)
mole fraction
of I2(g)
0.23
0.23
0
0
0
© UCLES 2021
time
time
0
9701/11/O/N/21
time
5
11 The diagram shows the Boltzmann distribution of energies for a reactant gas. For a particular
reaction, the activation energy is X.
number of
particles with
energy, E
0
X
0
energy, E
Which change to the diagram occurs if an effective catalyst is added at the same temperature?
A
More particles will possess higher values of E.
B
The peak will move to the left.
C
The peak will move to the right.
D
The value of the activation energy decreases.
12 Which element requires the least number of moles of oxygen for the complete combustion of
1 mol of its atoms?
A
aluminium
B
magnesium
C
phosphorus
D
sodium
13 An element, Y, reacts according to the following sequence.
burns
in O2
Y
HCl (aq)
white solid
an excess of
NaOH(aq)
NaOH(aq)
solution
white precipitate
solution
What could be element Y?
A
Na
B
Mg
C
Al
D
P
14 In which list are all three compounds soluble in water?
A
barium chloride, calcium carbonate, magnesium hydroxide
B
barium hydroxide, calcium hydroxide, strontium carbonate
C
barium chloride, barium hydroxide, magnesium sulfate
D
barium sulfate, calcium sulfate, magnesium hydroxide
© UCLES 2021
9701/11/O/N/21
[Turn over
6
15 Anhydrous magnesium nitrate, Mg(NO3)2, decomposes when heated, giving a white solid and a
mixture of two gases, X and Y.
Y is oxygen.
What is the ratio mass of X released ?
mass of Y released
1
1
A
B
C
0.174
0.267
1
0.348
1
3.43
D
16 In a series of nine experiments, to test the reactivity of the halogens, an aqueous solution of each
halogen is added to an equal volume of an aqueous solution containing halide ions, as shown in
the table.
halide solution
halogen
solution
sodium chloride (aq)
sodium bromide (aq)
sodium iodide (aq)
chlorine (aq)
experiment 1
experiment 2
experiment 3
bromine (aq)
experiment 4
experiment 5
experiment 6
iodine (aq)
experiment 7
experiment 8
experiment 9
The nine resulting mixtures are then shaken separately with an equal volume of hexane. The nine
tubes are left to stand so that the aqueous and organic solvents separate into layers.
How many test-tubes contain a purple upper hexane layer?
A
1
B
2
C
3
D
5
17 Z is a compound of sodium, chlorine and oxygen.
It contains 45.1% by mass of oxygen.
Z is prepared by reacting sodium hydroxide with chlorine.
Which row shows the conditions used for the reaction and the oxidation state of chlorine in Z?
reaction conditions
oxidation state of Cl in Z
A
cold dilute NaOH
+1
B
cold dilute NaOH
+5
C
hot concentrated NaOH
+1
D
hot concentrated NaOH
+5
© UCLES 2021
9701/11/O/N/21
7
18 Which row is correct?
shape
bonds present
ammonia
molecule
ammonium
ion
ammonia
molecule
ammonium
ion
A
pyramidal
regular tetrahedral


B
pyramidal
regular tetrahedral


C
regular tetrahedral
pyramidal


D
regular tetrahedral
pyramidal


19 The table describes two possible environmental consequences of adding too much ammonium
nitrate fertiliser to the soil.
Which row is correct?
increased plant
growth in rivers
photochemical
smog
A
B
C
D
20 Hex-2-ene can be made by the reaction shown.
O–
H
HO
+
I–
I
Which statement about this reaction is correct?
A
(CH3)3CO– is behaving as a Brønsted-Lowry base.
B
(CH3)3CO– is behaving as an oxidising agent.
C
The C–I bond breaks via homolytic fission.
D
This is a hydrolysis reaction.
© UCLES 2021
9701/11/O/N/21
[Turn over
8
21 Structural isomerism only should be considered when answering this question.
Molecule X contains three C=C double bonds. One mole of X is reacted with three moles of HBr.
The carbon skeleton is unchanged.
molecule X
How many different products are formed?
A
3
B
4
C
6
D
8
22 Structural isomerism and stereoisomerism should be considered when answering this question.
A colourless liquid, C5H11Cl , exists as a mixture of two optical isomers.
When heated with sodium hydroxide in ethanol, a mixture of only two alkenes is formed.
What could the colourless liquid be?
A
(CH3CH2)2CHCl
B
CH3CH2CH2CHCl CH3
C
CH3CH2CCl (CH3)2
D
(CH3)2CHCHCl CH3
23 When 2-bromo-2-methylpropane reacts with aqueous sodium hydroxide, an alcohol is formed.
Which diagram describes the first step in the reaction mechanism?
H 3C
A
B
C
D
CH3
CH3
CH3
CH3
G+
C
CH3
© UCLES 2021
Br
G–
H 3C
G+
C
CH3
Br
G–
H 3C
–
HO••
9701/11/O/N/21
G+
C
CH3
Br
G–
H 3C
–
HO••
G+
C
CH3
Br
G–
9
24 When an organic compound, Q, is treated with phosphorus pentachloride, fumes of hydrogen
chloride are evolved. When Q is warmed with acidified aqueous potassium dichromate(VI), the
solution turns green.
What is Q?
A
CH3CH2CHO
B
CH3CH2CO2H
C
CH3CH(OH)CH3
D
(CH3)3COH
25 Alcohol Y gives a yellow precipitate with alkaline aqueous iodine. It can be oxidised to give a
mixture of products including substance Z. Substance Z gives a red-brown precipitate with
Fehling’s solution.
Which alcohol could be Y?
A
CH3CH(OH)CH(CH3)CH2OH
B
CH3C(OH)(CH3)CH2CH2OH
C
CH3CH(OH)CH2CH(OH)CH3
D
CH2(OH)CH2CH(OH)CH2CH3
26 CH3CH2COCH2CH3 reacts with hydrogen cyanide to form an organic product called a
cyanohydrin.
Which statement is correct?
A
The cyanohydrin product has one chiral centre.
B
The cyanohydrin product is formed by electrophilic addition.
C
The cyanohydrin product is formed via an intermediate which contains a C–OH group.
D
The formation of the cyanohydrin product requires the use of cyanide ions as a catalyst.
27 Reduction of compound R with LiAl H4 gives the compound 4-methylpentane-2,3-diol.
What could be the identity of compound R?
A
O
O
O
© UCLES 2021
C
B
O
D
O
O
O
O
9701/11/O/N/21
[Turn over
10
28 Citric acid is found in lemon juice.
citric acid
HO2CCH2C(OH)(CO2H)CH2CO2H
Which volume of 0.40 mol dm–3 sodium hydroxide solution is required to neutralise a solution
containing 0.0050 mol of citric acid?
A
12.5 cm3
B
25.0 cm3
C
37.5 cm3
D
29 The structural formula of an ester is (CH3)2CHOCO(CH2)2CH3.
This ester is boiled with aqueous hydrochloric acid.
Which two products are formed?
A
propan-1-ol and butanoic acid
B
propan-2-ol and butanoic acid
C
propan-1-ol and propanoic acid
D
propan-2-ol and propanoic acid
© UCLES 2021
9701/11/O/N/21
50.0 cm3
11
30 The infra-red spectra of three organic compounds are shown.
100
spectrum 1
transmittance / %
50
0
4000
3000
2000
1500
wavenumber / cm–1
1000
500
3000
2000
1500
wavenumber / cm–1
1000
500
3000
2000
1500
wavenumber / cm–1
1000
500
100
spectrum 2
transmittance / %
50
0
4000
100
spectrum 3
transmittance / %
50
0
4000
What could the three compounds be?
spectrum 1
spectrum 2
spectrum 3
A
propanoic acid
propanone
propan-2-ol
B
propanone
propanoic acid
propan-2-ol
C
propanone
propan-2-ol
propanoic acid
D
propan-2-ol
propanoic acid
propanone
© UCLES 2021
9701/11/O/N/21
[Turn over
12
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 Which changes can be used to measure the rates of chemical reactions?
1
the decrease in concentration of a reactant per unit time
2
the rate of appearance of a product
3
the increase in total volume of gas per unit time at constant pressure
32 Iron reacts with steam to produce hydrogen and an oxide of iron.
3Fe(s) + 4H2O(g)
Fe3O4(s) + 4H2(g)
A system containing all four substances is at equilibrium.
Which changes will decrease the mass of Fe present at equilibrium?
1
addition of steam at constant pressure
2
increase in overall pressure
3
addition of an effective catalyst
33 Ethylene glycol, HOCH2CH2OH, is used as a de-icer. It allows ice to melt at temperatures
below 0 C.
Which statements are correct?
1
Ethylene glycol disrupts the extensive network of hydrogen bonds in ice.
2
Ethylene glycol molecules form hydrogen bonds with other ethylene glycol molecules.
3
Ethylene glycol molecules will dissolve in the water formed from the ice.
© UCLES 2021
9701/11/O/N/21
13
34 Which molecules contain at least one unpaired electron?
1
NO
2
NO2
3
NH3
35 Which elements form a chloride in which both covalent bonding and coordinate (dative covalent)
bonding are present?
1
Al
2
Si
3
Mg
36 Which statements about calcium oxide are correct?
1
It can be reduced by heating with magnesium.
2
It is produced when calcium nitrate is heated.
3
It reacts with cold water.
37 A diketo acid is a compound with two ketone groups and one carboxylic acid group.
limonene
terpinolene
Which statements about the reactions of limonene and terpinolene are correct?
1
When reacted with an excess of hydrogen and a nickel catalyst, limonene and terpinolene
produce the same compound.
2
An excess of hot concentrated acidified KMnO4 reacts with limonene and with terpinolene to
form different diketo acids.
3
The reactions of limonene and terpinolene with an excess of Br2 produce positional isomers
with the same number of chiral carbon atoms.
© UCLES 2021
9701/11/O/N/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
38 One molecule of dodecane, C12H26, is cracked, producing three product molecules, X, Y and Z.
X is a straight chain alkane. Y and Z are straight chain alkenes with different Mr values.
Which statements about X, Y and Z are correct?
1
If Y and Z are but-1-ene and ethene respectively, X will be hexane.
2
If X is butane, then Y and Z could both show cis-trans isomerism.
3
X could be octane.
39 Which statements about chlorofluoroalkanes are correct?
1
Both the C–Cl and C–F bonds are readily dissociated by ultra-violet light.
2
They have caused ozone depletion.
3
They are relatively chemically inert.
40 Which reactions of propan-1-ol have water as one of the products?
1
passing propan-1-ol vapour over hot Al 2O3
2
mixing propan-1-ol with warm ethanoic acid and a few drops of concentrated sulfuric acid
3
warming propan-1-ol with HBr
© UCLES 2021
9701/11/O/N/21
Cambridge International AS & A Level
CHEMISTRY
9701/12
Paper 1 Multiple Choice
October/November 2021
1 hour
You must answer on the multiple choice answer sheet.
*8531315998*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 11_9701_12/3RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
Compound X consists of 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass.
What is the empirical formula of compound X?
A
2
3
CH2O
B
C2H2O
C
C2H4O
D
CHO
Which statement is correct?
A
1.0 g of hydrogen gas contains 3.0  1023 atoms.
B
4.0 g of helium gas contains 1.2  1024 atoms.
C
16 g of methane gas contains 3.0  1024 atoms.
D
44 g of carbon dioxide gas contains 6.0  1023 atoms.
Technetium (Tc) is a second row transition element that does not occur naturally on Earth. One of
its isotopes has 56 neutrons.
What is the nucleon number of this isotope?
A
4
43
B
56
C
99
D
112
Which atom has more unpaired electrons than paired electrons in orbitals of principal quantum
number 2?
A
carbon
B
nitrogen
C
oxygen
D
fluorine
© UCLES 2021
9701/12/O/N/21
3
5
Atom X is the central atom in a molecule.
In this molecule, atom X has four pairs of valence electrons in its outer shell.
The four pairs of valence electrons include at least one bond pair and at least one lone pair.
What could be a possible shape for the molecule?
6
A
linear
B
non-linear
C
trigonal bipyramidal
D
trigonal planar
Which molecule has the largest overall dipole?
A
B
Cl
Cl
C
Cl
7
C
C
H
O
Cl
D
Cl
C
O
C
O
C
O
Cl
H
The strength of hydrogen bonding increases as the electronegativity of the element bonded to
hydrogen increases.
Some information for a range of hydrides is given.
hydride
boiling point
/K
PH3
185
HCl
188
HF
293
H2O
373
Which statement and reason about these hydrides is correct?
A
The boiling point of PH3 is much lower than the boiling point of H2O because PH3 does not
form hydrogen bonds or instantaneous dipole-induced dipole forces between its molecules.
B
The boiling point of HF is higher than the boiling point of HCl because the bond energy of
H–F is greater than the bond energy of H–Cl.
C
The boiling point of H2O is higher than the boiling point of HF because each hydrogen bond
between the H2O molecules is stronger than each hydrogen bond between HF molecules.
D
The boiling points of PH3 and HCl are similar because the molecules of PH3 and HCl have
the same number of electrons and similar intermolecular forces.
© UCLES 2021
9701/12/O/N/21
[Turn over
4
8
The general gas equation can be used to calculate the value of the Mr of a gas.
For a sample of a gas of mass m grams, which expression will give the value of Mr?
A
9
Mr =
mRT
pV
B
Mr =
pVRT
m
C
Mr =
mpV
RT
D
Mr =
pV
mRT
The equation for the formation of ammonium chloride is shown.
NH3(g) + HCl (g)
H = –314 kJ mol–1
NH4Cl (s)
Which diagram shows the correctly labelled reaction pathway diagram for the decomposition of
ammonium chloride?
A
EA
energy
B
NH3 + HCl
NH3 + HCl
NH4Cl
progress of reaction
progress of reaction
C
D
EA
NH4Cl
energy
∆H
NH3 + HCl
progress of reaction
© UCLES 2021
∆H
NH4Cl
NH4Cl
energy
EA
energy
∆H
EA
∆H
NH3 + HCl
progress of reaction
9701/12/O/N/21
5
10 In a catalytic converter in the exhaust system of a car, carbon monoxide is oxidised to carbon
dioxide, and nitrogen monoxide is reduced to nitrogen.
What are the changes in oxidation number of carbon and nitrogen in these two processes?
carbon
nitrogen
A
–2
+2
B
–1
+1
C
+1
–1
D
+2
–2
11 NO and NO2 are both present in the lower atmosphere as pollutants.
The reaction sequence shows the production of ozone from oxygen in the lower atmosphere.
This sequence repeats many times.
NO2(g)  NO(g) + O(g)
NO(g) +
1
2
O2(g)  NO2(g)
O2(g) + O(g)  O3(g)
Which statement about this reaction sequence is correct?
A
NO is acting as a catalyst, but NO2 is not acting as a catalyst.
B
NO2 is acting as a catalyst, but NO is not acting as a catalyst.
C
Neither NO nor NO2 are acting as catalysts.
D
Both NO and NO2 are acting as catalysts.
12 A mixture of two Period 3 oxides are added to water. A solution forms with a pH of just below 7.
What could be the constituents of the mixture?
A
Al 2O3 and MgO
B
Na2O and MgO
C
Na2O and P4O10
D
SO3 and P4O10
© UCLES 2021
9701/12/O/N/21
[Turn over
6
13 Which statement about the compounds of the Group 2 metals is correct?
A
Barium carbonate is less thermally stable than strontium carbonate.
B
Barium sulfate is less soluble than magnesium sulfate.
C
Calcium hydroxide is less soluble than magnesium hydroxide.
D
Calcium nitrate is more thermally stable than strontium nitrate.
14 A 0.005 mol sample of anhydrous calcium carbonate is completely thermally decomposed to give
100 cm3 of gas.
In a separate experiment carried out under the same conditions, a 0.005 mol sample of
anhydrous calcium nitrate is completely thermally decomposed. The volume of gaseous products
is measured.
What total volume of gaseous products is produced from the calcium nitrate?
A
50 cm3
B
100 cm3
C
200 cm3
D
250 cm3
15 Redox reactions are common in the chemistry of Group 17 elements.
Which statement is correct?
A
Br – ions will reduce Cl 2 but not I2.
B
Cl 2 will oxidise Br – ions but not I– ions.
C
F2 is the weakest oxidising agent out of F2, Cl 2, Br2 and I2.
D
I– ions are the weakest reducing agent out of F –, Cl –, Br – and I–.
© UCLES 2021
9701/12/O/N/21
7
16 Silver chloride and silver iodide form equilibria when added to water.
AgCl (s)
Ag+(aq) + Cl –(aq)
Kc = K1
AgI(s)
Ag+(aq) + I–(aq)
Kc = K2
Each equilibrium position lies well to the left.
Silver iodide will not dissolve in aqueous ammonia. Silver chloride will dissolve in aqueous
ammonia. Another equilibrium is formed.
Ag+(aq) + 2NH3(aq)
Ag(NH3)2+(aq)
Kc = K3
The position of this equilibrium lies to the right.
What is the order of magnitude for these three equilibrium constants?
smallest
largest
A
K3
K2
K1
B
K3
K1
K2
C
K2
K1
K3
D
K1
K2
K3
17 X is the ion of a metal which burns with a red flame.
Y is an ion that reacts with concentrated H2SO4 to produce H2S.
What could be the formula of a compound containing X and Y?
A
BaBr2
B
BaI2
C
SrBr2
D
SrI2
18 Oxides of nitrogen are present in the environment due to natural and man-made sources.
Which row is correct?
natural source of nitrogen oxides
man-made source of nitrogen oxides
A
electrical discharges in the atmosphere
internal combustion engines
B
electrical discharges in the atmosphere
as a by-product of the Haber process
C
decomposition of dead plants in rivers
internal combustion engines
D
decomposition of dead plants in rivers
as a by-product of the Haber process
© UCLES 2021
9701/12/O/N/21
[Turn over
8
19 Magnesium hydroxide dissolves in aqueous ammonium chloride, but not in aqueous sodium
chloride.
Which statement explains this observation?
A
The ionic radius of the NH4+ ion is similar to that of Mg2+ but not that of Na+.
B
NH4Cl dissociates less fully than NaCl.
C
The Na+ and Mg2+ ions have the same number of electrons.
D
The NH4+ ion can donate a proton.
20 The formula of hydrocortisone acetate is shown.
hydrocortisone acetate
HO
O
CH2OCOCH3
CH3
OH
CH3
O
Which row is correct?
number of C atoms
in one molecule
number of chiral atoms
in one molecule
A
22
7
B
22
8
C
23
7
D
23
8
21 Bromomethane, CH3Br, decomposes in the stratosphere forming methyl free radicals and
bromine free radicals.
Which row correctly describes this decomposition?
type of bond fission
number of electrons in
a bromine free radical
A
homolytic
35
B
heterolytic
35
C
homolytic
36
D
heterolytic
36
© UCLES 2021
9701/12/O/N/21
9
22 Structural and stereoisomerism should be taken into account when answering this question.
Y is a gaseous hydrocarbon which decolourises aqueous bromine. It contains no rings.
10.0 g of Y occupies a volume of 3.43 dm3 under room conditions.
How many isomeric structures are possible for Y?
A
4
B
5
C
6
D
7
23 Which equation represents a valid propagation step in the chlorination of ethane?
A
C2H5Cl + Cl •  C2H4Cl • + HCl
B
C2H6 + Cl •  C2H5Cl + H•
C
C2H5Cl + H•  C2H5• + HCl
D
C2H5• + Cl •  C2H5Cl
24 Butanoic acid can be made from 1-bromopropane in two stages.
stage 1
CH3CH2CH2Br  CH3CH2CH2CN
stage 2
CH3CH2CH2CN  CH3CH2CH2CO2H
Which types of reaction are stage 1 and stage 2?
stage 1
stage 2
A
electrophilic addition
hydrolysis
B
electrophilic addition
oxidation
C
nucleophilic substitution
hydrolysis
D
nucleophilic substitution
oxidation
25 A halogenoalkane has the molecular formula C5H11Br. The halogenoalkane does not form an
alkene when treated with ethanolic sodium hydroxide.
What could be the halogenoalkane?
A
1-bromo-2-methylbutane
B
2-bromo-2-methylbutane
C
3-bromopentane
D
1-bromo-2,2-dimethylpropane
© UCLES 2021
9701/12/O/N/21
[Turn over
10
26 Compound P is heated under reflux with an excess of acidified potassium dichromate(VI) to form
compound Q.
Compound Q has a lower boiling point than compound P.
What could be compound P?
A
2-methylbutan-1-ol
B
2-methylbutan-2-ol
C
pentan-1-ol
D
pentan-2-ol
27 Structural and stereoisomerism should be taken into account when answering this question.
An organic compound, X, is dehydrated by heating with concentrated phosphoric(V) acid.
Only two organic products are formed.
What could be X?
A
B
D
C
OH
OH
OH
OH
OH
28 Which compound produces a precipitate with 2,4-dinitrophenylhydrazine reagent and also with
alkaline aqueous iodine?
A
butan-2-ol
B
butanal
C
butanone
D
pentan-3-one
© UCLES 2021
9701/12/O/N/21
11
29 Organic compound Z has an alcohol group and a carboxylic acid group.
Compound Z reacts with magnesium carbonate to make a salt with a relative formula mass of
230.3.
Compound Z does not react with acidified potassium manganate(VII).
What could be the identity of compound Z?
A
2-hydroxy-2-methylbutanoic acid
B
2-hydroxy-2-methylpropanoic acid
C
3-hydroxy-2-methylbutanoic acid
D
3-hydroxy-2-methylpropanoic acid
30 The infra-red spectrum of Y is shown.
100
transmittance / %
50
0
4000
3000
2000
1500
1000
500
wavenumber / cm–1
What could Y be?
A
CH3CO2C2H5
B
CH2(OH)CH=CHCH2OH
C
CH3(CH2)2CO2H
D
CH2(OH)(CH2)2CHO
© UCLES 2021
9701/12/O/N/21
[Turn over
12
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 The Boltzmann distribution diagram shows a fixed amount of a gas at two different temperatures,
T1 and T2.
T1
T2
activation
energy
number of
particles with
energy, E
0
0
molecular energy, E
Which statements correctly describe the features of this diagram?
1
Temperature T1 is lower than temperature T2.
2
The shaded area indicates the particles that have sufficient energy to react at T2.
3
The total area under each curve is the same for both temperatures.
© UCLES 2021
9701/12/O/N/21
13
32 Four solutions, each of concentration 0.1 mol dm–3, were tested with a pH meter. The results are
shown.
solution
formula of acid or base
pH
acid 1
CH3CO2H
4
acid 2
HNO3
1
base 1
CH3NH2
11
base 2
NaOH
14
Which statements explain these results?
1
Acid 2 has a lower pH than acid 1 because it is more soluble.
2
Base 2 has a higher concentration of hydroxide ions in solution than base 1.
3
Acid 1 dissociates less than acid 2.
33 Which reactions are redox reactions?
1
Mg + 2HCl  MgCl 2 + H2
2
2K2CrO4 + 2H+  K2Cr2O7 + 2K+ + H2O
3
CuCO3 + 2HCl  CuCl 2 + H2O + CO2
34 When the liquid N2F4 is heated, it decomposes into a single product, X.
Which statements are correct?
1
N–F bonds are broken during this decomposition.
2
The enthalpy change when N2F4 decomposes into X is approximately +160 kJ mol–1.
3
Molecules of X are non-linear.
35 The following statements compare some properties of the oxides and chlorides of sodium and
silicon.
Which statements are correct?
1
The melting point of SiCl 4 is higher than the melting point of SiO2.
2
SiCl 4 reacts with water, NaCl does not.
3
The melting point of SiCl 4 is lower than the melting point of NaCl.
© UCLES 2021
9701/12/O/N/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
36 Which statements about ammonium chloride are correct?
1
It reacts with hot aqueous sodium hydroxide to produce an alkaline gas.
2
In solution, it reacts with aqueous silver nitrate to produce a white precipitate.
3
When solid, it reacts with concentrated sulfuric acid to produce chlorine.
37 What is the same for a pair of optical isomers?
1
their empirical formula
2
their functional groups
3
their structural formula
38 Which of the molecular formulae represent at least one compound that can undergo addition
polymerisation?
1
C4H8
2
C2H3Cl
3
C3H6O
39 Which of the reactions give products containing a chiral centre?
1
CH2(OH)COCO2H + an excess of HCN
2
CH2(OH)COCO2H + an excess of NaBH4
3
CH2(OH)COCO2H + an excess of LiAl H4
40 Ethyl butanoate is heated with a dilute aqueous solution of sodium hydroxide.
Which substances are products of this reaction?
1
sodium butanoate
2
water
3
sodium ethanoate
© UCLES 2021
9701/12/O/N/21
Cambridge International AS & A Level
CHEMISTRY
9701/13
Paper 1 Multiple Choice
October/November 2021
1 hour
You must answer on the multiple choice answer sheet.
*5055836996*
You will need: Multiple choice answer sheet
Soft clean eraser
Soft pencil (type B or HB is recommended)
Data booklet
INSTRUCTIONS
 There are forty questions on this paper. Answer all questions.
 For each question there are four possible answers A, B, C and D. Choose the one you consider correct
and record your choice in soft pencil on the multiple choice answer sheet.
 Follow the instructions on the multiple choice answer sheet.
 Write in soft pencil.
 Write your name, centre number and candidate number on the multiple choice answer sheet in the
spaces provided unless this has been done for you.
 Do not use correction fluid.
 Do not write on any bar codes.
 You may use a calculator.
INFORMATION
 The total mark for this paper is 40.
 Each correct answer will score one mark.
 Any rough working should be done on this question paper.
This document has 16 pages. Any blank pages are indicated.
IB21 11_9701_13/3RP
© UCLES 2021
[Turn over
2
Section A
For each question there are four possible answers A, B, C and D. Choose the one you consider to be
correct.
Use of the Data Booklet may be appropriate for some questions.
1
The mass spectrum of a sample of neon is shown. The relative abundance of each peak is
written in brackets above it.
(100)
relative
abundance
(8)
(0.3)
20
21
22
mass
charge
What is the relative atomic mass, Ar, of this sample of neon?
A
2
20.15
B
20.20
C
21.00
D
21.82
2.0 g of ammonium nitrate, NH4NO3, decomposes to give 0.90 g of water and a single gas.
What is the identity of the gas?
A
3
B
NO2
C
N2O
D
N2
Which of these elements has the highest fifth ionisation energy?
A
4
NO
C
B
N
C
P
D
The ion X2+ has the same electronic configuration as the atom Kr.
What is the electronic configuration of an atom of X?
A
[Ar] 4s23d104p6
B
[Ar] 4s23d104p65s2
C
[Ar] 4s24d104p6
D
[Ar] 4s24d104p65s2
© UCLES 2021
9701/13/O/N/21
Si
3
5
6
Which type of interaction exists between water molecules and metal cations in aqueous solution?
A
dipole-dipole interactions
B
hydrogen bonds
C
ion-dipole interactions
D
ionic bonds
Which substance shows the greatest deviation from the properties of an ideal gas under room
conditions?
A
7
CO2(g)
B
H2(g)
C
Ne(g)
D
NH3(g)
In order to determine the enthalpy of neutralisation of a strong acid and a strong alkali, 25.0 cm3
of 2.00 mol dm‒3 sodium hydroxide is added to 25.0 cm3 of 2.00 mol dm‒3 hydrochloric acid. The
increase in temperature is 12 C.
In a second experiment, the same method is used, but 50.0 cm3 of 2.00 mol dm‒3
sodium hydroxide is added to 50.0 cm3 of 2.00 mol dm‒3 hydrochloric acid.
What is the increase in temperature in the second experiment?
A
8
9
6 C
B
12 C
C
24 C
D
48 C
Which equation represents the enthalpy change of atomisation of iodine?
A
1
I (g)
2 2
 I(g)
B
I2(g)  2I(g)
C
1
I (s)
2 2
D
I2(s)  2I(g)
 I(g)
Zinc atoms can be oxidised to Zn2+ ions by dichromate(VI) ions in acid solution. Chromium is
reduced to Cr3+ in this reaction.
Which equation is correct?
A
Cr2O72– + Zn + 14H+  2Cr3+ + Zn2+ + 7H2O
B
Cr2O72– + Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
C
Cr2O72– + 3Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
D
2Cr2O72– + 3Zn + 14H+  2Cr3+ + 3Zn2+ + 7H2O
© UCLES 2021
9701/13/O/N/21
[Turn over
4
10 The equation shows that H2(g) and I2(g) react to form an equilibrium mixture.
H2(g) + I2(g)
H o = –9.6 kJ mol–1
2HI(g)
A mixture containing equal amounts of H2(g) and I2(g) is made at temperature T1 and the
composition of the mixture is monitored. A graph of the results is shown.
0.5
mole fraction
of I2(g)
0.23
0
time
0
The experiment is repeated at a lower temperature, T2.
Which new graph would be obtained?
A
B
0.5
0.5
mole fraction
of I2(g)
mole fraction
of I2(g)
0.23
0.23
0
0
0
time
0
C
D
0.5
0.5
mole fraction
of I2(g)
mole fraction
of I2(g)
0.23
0.23
0
0
0
© UCLES 2021
time
time
0
9701/13/O/N/21
time
5
11 The diagram shows the Boltzmann distribution of energies for a reactant gas. For a particular
reaction, the activation energy is X.
number of
particles with
energy, E
0
X
0
energy, E
Which change to the diagram occurs if an effective catalyst is added at the same temperature?
A
More particles will possess higher values of E.
B
The peak will move to the left.
C
The peak will move to the right.
D
The value of the activation energy decreases.
12 Which element requires the least number of moles of oxygen for the complete combustion of
1 mol of its atoms?
A
aluminium
B
magnesium
C
phosphorus
D
sodium
13 An element, Y, reacts according to the following sequence.
burns
in O2
Y
HCl (aq)
white solid
an excess of
NaOH(aq)
NaOH(aq)
solution
white precipitate
solution
What could be element Y?
A
Na
B
Mg
C
Al
D
P
14 In which list are all three compounds soluble in water?
A
barium chloride, calcium carbonate, magnesium hydroxide
B
barium hydroxide, calcium hydroxide, strontium carbonate
C
barium chloride, barium hydroxide, magnesium sulfate
D
barium sulfate, calcium sulfate, magnesium hydroxide
© UCLES 2021
9701/13/O/N/21
[Turn over
6
15 Anhydrous magnesium nitrate, Mg(NO3)2, decomposes when heated, giving a white solid and a
mixture of two gases, X and Y.
Y is oxygen.
What is the ratio mass of X released ?
mass of Y released
1
1
A
B
C
0.174
0.267
1
0.348
1
3.43
D
16 In a series of nine experiments, to test the reactivity of the halogens, an aqueous solution of each
halogen is added to an equal volume of an aqueous solution containing halide ions, as shown in
the table.
halide solution
halogen
solution
sodium chloride (aq)
sodium bromide (aq)
sodium iodide (aq)
chlorine (aq)
experiment 1
experiment 2
experiment 3
bromine (aq)
experiment 4
experiment 5
experiment 6
iodine (aq)
experiment 7
experiment 8
experiment 9
The nine resulting mixtures are then shaken separately with an equal volume of hexane. The nine
tubes are left to stand so that the aqueous and organic solvents separate into layers.
How many test-tubes contain a purple upper hexane layer?
A
1
B
2
C
3
D
5
17 Z is a compound of sodium, chlorine and oxygen.
It contains 45.1% by mass of oxygen.
Z is prepared by reacting sodium hydroxide with chlorine.
Which row shows the conditions used for the reaction and the oxidation state of chlorine in Z?
reaction conditions
oxidation state of Cl in Z
A
cold dilute NaOH
+1
B
cold dilute NaOH
+5
C
hot concentrated NaOH
+1
D
hot concentrated NaOH
+5
© UCLES 2021
9701/13/O/N/21
7
18 Which row is correct?
shape
bonds present
ammonia
molecule
ammonium
ion
ammonia
molecule
ammonium
ion
A
pyramidal
regular tetrahedral


B
pyramidal
regular tetrahedral


C
regular tetrahedral
pyramidal


D
regular tetrahedral
pyramidal


19 The table describes two possible environmental consequences of adding too much ammonium
nitrate fertiliser to the soil.
Which row is correct?
increased plant
growth in rivers
photochemical
smog
A
B
C
D
20 Hex-2-ene can be made by the reaction shown.
O–
H
HO
+
I–
I
Which statement about this reaction is correct?
A
(CH3)3CO– is behaving as a Brønsted-Lowry base.
B
(CH3)3CO– is behaving as an oxidising agent.
C
The C–I bond breaks via homolytic fission.
D
This is a hydrolysis reaction.
© UCLES 2021
9701/13/O/N/21
[Turn over
8
21 Structural isomerism only should be considered when answering this question.
Molecule X contains three C=C double bonds. One mole of X is reacted with three moles of HBr.
The carbon skeleton is unchanged.
molecule X
How many different products are formed?
A
3
B
4
C
6
D
8
22 Structural isomerism and stereoisomerism should be considered when answering this question.
A colourless liquid, C5H11Cl , exists as a mixture of two optical isomers.
When heated with sodium hydroxide in ethanol, a mixture of only two alkenes is formed.
What could the colourless liquid be?
A
(CH3CH2)2CHCl
B
CH3CH2CH2CHCl CH3
C
CH3CH2CCl (CH3)2
D
(CH3)2CHCHCl CH3
23 When 2-bromo-2-methylpropane reacts with aqueous sodium hydroxide, an alcohol is formed.
Which diagram describes the first step in the reaction mechanism?
H 3C
A
B
C
D
CH3
CH3
CH3
CH3
G+
C
CH3
© UCLES 2021
Br
G–
H 3C
G+
C
CH3
Br
G–
H 3C
–
HO••
9701/13/O/N/21
G+
C
CH3
Br
G–
H 3C
–
HO••
G+
C
CH3
Br
G–
9
24 When an organic compound, Q, is treated with phosphorus pentachloride, fumes of hydrogen
chloride are evolved. When Q is warmed with acidified aqueous potassium dichromate(VI), the
solution turns green.
What is Q?
A
CH3CH2CHO
B
CH3CH2CO2H
C
CH3CH(OH)CH3
D
(CH3)3COH
25 Alcohol Y gives a yellow precipitate with alkaline aqueous iodine. It can be oxidised to give a
mixture of products including substance Z. Substance Z gives a red-brown precipitate with
Fehling’s solution.
Which alcohol could be Y?
A
CH3CH(OH)CH(CH3)CH2OH
B
CH3C(OH)(CH3)CH2CH2OH
C
CH3CH(OH)CH2CH(OH)CH3
D
CH2(OH)CH2CH(OH)CH2CH3
26 CH3CH2COCH2CH3 reacts with hydrogen cyanide to form an organic product called a
cyanohydrin.
Which statement is correct?
A
The cyanohydrin product has one chiral centre.
B
The cyanohydrin product is formed by electrophilic addition.
C
The cyanohydrin product is formed via an intermediate which contains a C–OH group.
D
The formation of the cyanohydrin product requires the use of cyanide ions as a catalyst.
27 Reduction of compound R with LiAl H4 gives the compound 4-methylpentane-2,3-diol.
What could be the identity of compound R?
A
O
O
O
© UCLES 2021
C
B
O
D
O
O
O
O
9701/13/O/N/21
[Turn over
10
28 Citric acid is found in lemon juice.
citric acid
HO2CCH2C(OH)(CO2H)CH2CO2H
Which volume of 0.40 mol dm–3 sodium hydroxide solution is required to neutralise a solution
containing 0.0050 mol of citric acid?
A
12.5 cm3
B
25.0 cm3
C
37.5 cm3
D
29 The structural formula of an ester is (CH3)2CHOCO(CH2)2CH3.
This ester is boiled with aqueous hydrochloric acid.
Which two products are formed?
A
propan-1-ol and butanoic acid
B
propan-2-ol and butanoic acid
C
propan-1-ol and propanoic acid
D
propan-2-ol and propanoic acid
© UCLES 2021
9701/13/O/N/21
50.0 cm3
11
30 The infra-red spectra of three organic compounds are shown.
100
spectrum 1
transmittance / %
50
0
4000
3000
2000
1500
wavenumber / cm–1
1000
500
3000
2000
1500
wavenumber / cm–1
1000
500
3000
2000
1500
wavenumber / cm–1
1000
500
100
spectrum 2
transmittance / %
50
0
4000
100
spectrum 3
transmittance / %
50
0
4000
What could the three compounds be?
spectrum 1
spectrum 2
spectrum 3
A
propanoic acid
propanone
propan-2-ol
B
propanone
propanoic acid
propan-2-ol
C
propanone
propan-2-ol
propanoic acid
D
propan-2-ol
propanoic acid
propanone
© UCLES 2021
9701/13/O/N/21
[Turn over
12
Section B
For each of the questions in this section, one or more of the three numbered statements 1 to 3 may
be correct.
Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against
the statements that you consider to be correct).
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
Use of the Data Booklet may be appropriate for some questions.
31 Which changes can be used to measure the rates of chemical reactions?
1
the decrease in concentration of a reactant per unit time
2
the rate of appearance of a product
3
the increase in total volume of gas per unit time at constant pressure
32 Iron reacts with steam to produce hydrogen and an oxide of iron.
3Fe(s) + 4H2O(g)
Fe3O4(s) + 4H2(g)
A system containing all four substances is at equilibrium.
Which changes will decrease the mass of Fe present at equilibrium?
1
addition of steam at constant pressure
2
increase in overall pressure
3
addition of an effective catalyst
33 Ethylene glycol, HOCH2CH2OH, is used as a de-icer. It allows ice to melt at temperatures
below 0 C.
Which statements are correct?
1
Ethylene glycol disrupts the extensive network of hydrogen bonds in ice.
2
Ethylene glycol molecules form hydrogen bonds with other ethylene glycol molecules.
3
Ethylene glycol molecules will dissolve in the water formed from the ice.
© UCLES 2021
9701/13/O/N/21
13
34 Which molecules contain at least one unpaired electron?
1
NO
2
NO2
3
NH3
35 Which elements form a chloride in which both covalent bonding and coordinate (dative covalent)
bonding are present?
1
Al
2
Si
3
Mg
36 Which statements about calcium oxide are correct?
1
It can be reduced by heating with magnesium.
2
It is produced when calcium nitrate is heated.
3
It reacts with cold water.
37 A diketo acid is a compound with two ketone groups and one carboxylic acid group.
limonene
terpinolene
Which statements about the reactions of limonene and terpinolene are correct?
1
When reacted with an excess of hydrogen and a nickel catalyst, limonene and terpinolene
produce the same compound.
2
An excess of hot concentrated acidified KMnO4 reacts with limonene and with terpinolene to
form different diketo acids.
3
The reactions of limonene and terpinolene with an excess of Br2 produce positional isomers
with the same number of chiral carbon atoms.
© UCLES 2021
9701/13/O/N/21
[Turn over
14
The responses A to D should be selected on the basis of
A
B
C
D
1, 2 and 3
are
correct
1 and 2
only are
correct
2 and 3
only are
correct
1 only
is
correct
No other combination of statements is used as a correct response.
38 One molecule of dodecane, C12H26, is cracked, producing three product molecules, X, Y and Z.
X is a straight chain alkane. Y and Z are straight chain alkenes with different Mr values.
Which statements about X, Y and Z are correct?
1
If Y and Z are but-1-ene and ethene respectively, X will be hexane.
2
If X is butane, then Y and Z could both show cis-trans isomerism.
3
X could be octane.
39 Which statements about chlorofluoroalkanes are correct?
1
Both the C–Cl and C–F bonds are readily dissociated by ultra-violet light.
2
They have caused ozone depletion.
3
They are relatively chemically inert.
40 Which reactions of propan-1-ol have water as one of the products?
1
passing propan-1-ol vapour over hot Al 2O3
2
mixing propan-1-ol with warm ethanoic acid and a few drops of concentrated sulfuric acid
3
warming propan-1-ol with HBr
© UCLES 2021
9701/13/O/N/21
Cambridge International AS & A Level
*7997951444*
CHEMISTRY9701/21
Paper 2 AS Level Structured Questions
October/November 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 16 pages. Any blank pages are indicated.
IB21 11_9701_21/FP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1
Sulfides are compounds that contain sulfur but not oxygen.
(a) Carbon disulfide, CS2, is a volatile liquid at room temperature and pressure.
(i)
State the meaning of volatile.
........................................................................................................................................ [1]
(ii)
Draw a ‘dot-and-cross’ diagram of the CS2 molecule.
[2]
(iii)
Suggest the bond angle in a molecule of CS2.
........................................................................................................................................ [1]
(iv)CS2 is a liquid under room conditions, while CO2 is a gas.
Explain what causes the difference in the physical properties between CS2 and CO2.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/21/O/N/21
3
(b) The enthalpy change of combustion of CS2(l) is represented by the following equation.
CS2(l) + 3O2(g) (i)
∆Hc
CO2(g) + 2SO2(g)
Define enthalpy change of combustion.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)
The table shows the enthalpy changes of formation of CS2(l), CO2(g) and SO2(g).
compound
enthalpy change of
formation, ∆Hf / kJ mol–1
CS2(l)
+89.7
CO2(g)
–394
SO2(g)
–297
se the data in the table to calculate the enthalpy change of combustion, ∆Hc, of CS2(l), in
U
kJ mol–1.
Show your working.
∆Hc of CS2(l) = .............................. kJ mol–1
[2]
© UCLES 2021
9701/21/O/N/21
[Turn over
4
(c) H
ydrogen sulfide gas, H2S(g), is slightly soluble in water. It acts as a weak acid in aqueous
solution.
(i)
State the meaning of weak acid.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Give the formula of the conjugate base of H2S.
........................................................................................................................................ [1]
(iii)H2S(aq) reacts slowly with oxygen dissolved in water. The reaction is represented by the
following equation.
H2S(aq) + 12 O2(aq) → H2O(l) + S(s)
Explain, with reference to oxidation numbers, why this reaction is a redox reaction.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/21/O/N/21
5
(d) The compound As2S3 is a common mineral.
When As2S3 is heated strongly in air, it forms a mixture of products, as shown.
2As2S3(s) + 9O2(g) → As4O6(s) + 6SO2(g)
(i)
sample containing 0.198 g As2S3 is placed in 0.100 dm3 of pure oxygen, an excess, in a
A
reaction chamber connected to a gas syringe at room temperature.
he reactants are heated until no further change is observed. The products are then
T
allowed to cool to room temperature.
Calculate the volume, in dm3, of gas present at the end of the experiment.
he molar volume of gas is 24.0 dm3 mol–1 under these conditions. Assume that the
T
pressure is constant throughout the experiment.
Show your working.
volume of gas remaining = ............................. dm3
[4]
(ii)
State the environmental consequences of releasing SO2(g) into the atmosphere.
........................................................................................................................................ [1]
(iii)
SO2(g) can be removed from the air by reacting it with NaOH(aq).
Construct an equation for the reaction of SO2(g) with NaOH(aq). Include state symbols.
........................................................................................................................................ [2]
© UCLES 2021
[Total: 21]
9701/21/O/N/21
[Turn over
6
2
The reaction scheme shows some reactions of calcium.
Ca(s)
reaction 1
HNO3
Ca(NO3)2(aq)
NaOH(aq)
heat
reaction 2 CO2(g)
CaO(s)
reaction 4 C(s)
CaC2(s)
(a) (i)
Ca(OH)2(aq)
CaCO3(s) + H2O(l)
reaction 3 excess CO2(g)
Ca(HCO3)2(aq)
Reaction 1 produces Ca(NO3)2 and one other product.
Identify the other product.
........................................................................................................................................ [1]
(ii)
Construct an equation for the thermal decomposition of Ca(NO3)2(s).
........................................................................................................................................ [1]
(iii)
State the trend in the thermal stability of the Group 2 nitrates down the group.
........................................................................................................................................ [1]
(iv)
In reaction 3, excess CO2 is bubbled through water containing CaCO3. A solution of
Ca(HCO3)2(aq) forms.
Construct an equation for reaction 3.
........................................................................................................................................ [1]
(b) Describe how Ca(OH)2 is used in agriculture.
.....................................................................................................................................................
............................................................................................................................................... [1]
© UCLES 2021
9701/21/O/N/21
7
(c) In reaction 4, calcium carbide, CaC2, is formed from CaO.
CaC2 contains the C22– anion. Each carbon in C22– is sp hybridised.
(i)
Describe how sp hybridised orbitals are formed.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Sketch a diagram to show how two sp hybrid orbitals can form a sigma (σ) bond.
[2]
© UCLES 2021
9701/21/O/N/21
[Turn over
8
(d) The flowchart shows some reactions of CaC2.
CaC2
N2
CaCN2
reaction 5
H 2O
CaCO3 + NH3
NaCl and C
NaCN
(i)
Reaction 5 can be used to prepare NH3.
CaCN2 + 3H2O → CaCO3 + 2NH3
alculate the minimum mass, in tonnes, of calcium cyanamide, CaCN2, that is required to
C
produce 1.50 × 106 tonnes of NH3.
Show your working.
1 tonne = 1.00 × 106 g
minimum mass of CaCN2 = .............................. tonnes
[2]
(ii)
CH3CH2Br
O
Draw the structure of the organic products formed in the following reactions.
H2SO4(aq)
NaCN
dissolved
in ethanol
heat under
reflux
NaCN
and HCN
[3]
© UCLES 2021
[Total: 13]
9701/21/O/N/21
9
3
Phosphorus is a reactive Period 3 element.
(a) Phosphorus has several allotropes. Details of two allotropes are given.
(i)
allotrope of phosphorus
formula
melting point / °C
white
P4
44
red
P
590
White phosphorus and red phosphorus both have covalent bonding.
Suggest the types of structure shown by white phosphorus (P4) and red phosphorus (P).
Explain why red phosphorus (P) has a higher melting point than white phosphorus (P4).
structure of P4 ......................................................................................................................
structure of P .......................................................................................................................
explanation ..........................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
[3]
(ii)
Red phosphorus (P) forms when white phosphorus (P4) is exposed to sunlight.
1
4 P4(s)
→ P(s)
white
red
∆H = –17.6 kJ mol–1
Use this information to draw a reaction pathway diagram to show the formation of red
phosphorus (P) from white phosphorus (P4).
enthalpy
P4
progress of reaction
[1]
© UCLES 2021
9701/21/O/N/21
[Turn over
10
(b) Some reactions of P4(s) are shown in the reaction scheme.
P4(s)
excess Cl 2(g)
H2O(l)
excess O2(g)
P4O10(s)
(i)
PCl 5(s)
reaction 2
H2O(l)
reaction 1
Q
State the oxidation number of phosphorus in P4O10.
........................................................................................................................................ [1]
(ii)
Deduce the identity of Q and hence construct chemical equations for reactions 1 and 2.
reaction 1
PCl 5 + .......H2O → ...............................................................................................
reaction 2 P4O10 + .......H2O → ..............................................................................................
[2]
(c) Triphenylphosphine is used in a type of reaction known as a Wittig reaction.
triphenylphosphine
P
(i)
where
= –C6H5
Give the empirical formula of triphenylphosphine.
........................................................................................................................................ [1]
© UCLES 2021
9701/21/O/N/21
11
In a Wittig reaction, an aldehyde reacts with a halogenoalkane to form an alkene. The conversion
is shown in the following unbalanced equation.
O
R
1
H
+
I
R2
R2
triphenylphosphine
strong base
R1
H
Compound H can be made from propanal, C2H5CHO. Stage 3 in the reaction scheme is a
Wittig reaction.
stage 1
C2H5CHO
stage 2
G
stage 3
(Wittig reaction)
(ii)
C2H5CH2I + C2H5CHO
NaBH4
G
red phosphorus and I2
triphenylphosphine
strong base
C2H5CH2I
H
State the types of reaction that occur in stages 1 and 2.
stage 1 .................................................................................................................................
stage 2 .................................................................................................................................
[2]
(iii)
Draw the structures of G and H in the boxes provided.
G
H
[2]
(d) Identify the organic products formed when compound J, shown below, is heated with hot
concentrated acidified manganate(VII) ions.
J
hot concentrated MnO4–
H2SO4
[2]
© UCLES 2021
[Total: 14]
9701/21/O/N/21
[Turn over
12
4
Compound B is a liquid with a fruity smell.
B
O
Br
O
The reaction scheme shows how B can be made from ethanol, C2H5OH.
C2H5OH
O
reaction 1
[O]
O
reaction 2
HO
Br
HO
C2H5OH
and H2SO4
reaction 3
B
O
O
(a) (i)
Br
Reaction 1 is an oxidation reaction.
Give the reagent(s) and conditions required for reaction 1.
reagent(s) ............................................................................................................................
conditions ............................................................................................................................
..............................................................................................................................................
[2]
(ii)Construct an equation to represent reaction 1.
Use [O] to represent an oxygen atom from the oxidising agent in this reaction.
........................................................................................................................................ [1]
(iii)
Suggest the type of reaction that occurs in reaction 2.
........................................................................................................................................ [1]
(iv)H2SO4 acts as a homogeneous catalyst in reaction 3.
Explain why H2SO4 is described as homogeneous.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/21/O/N/21
13
(b) Reaction 2 needs to take place in the absence of water to prevent formation of compound C.
C
O
HO
OH
If C is present in the reaction mixture of reaction 3, a different compound, compound D, will
also form. Compound D has two identical functional groups.
he infrared spectrum of D shows strong absorptions at 1100 cm–1 and 1720 cm–1, but no
T
absorption due to O–H bonds.
Use the Data Booklet to identify the functional group present in D.
Explain your answer as fully as you can.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
© UCLES 2021
9701/21/O/N/21
[Turn over
14
(c) Some other reactions of C are shown.
C
O
HO
OH
Na2CO3
E
(i)
F
(CH2OH)2
SOCl 2
G
(CH2Cl )2
Draw the structure of E.
[1]
(ii)
Suggest why NaBH4 is not a suitable reagent to make F, (CH2OH)2, from C.
xplain your answer.
E
..............................................................................................................................................
........................................................................................................................................ [1]
(iii)
Construct an equation for the reaction of (CH2OH)2 with SOCl 2 to form G, (CH2Cl )2.
........................................................................................................................................ [1]
(d) Explain why C is very soluble in water.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [1]
© UCLES 2021
[Total: 12]
9701/21/O/N/21
Cambridge International AS & A Level
*2578092005*
CHEMISTRY9701/22
Paper 2 AS Level Structured Questions
October/November 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 12 pages.
IB21 11_9701_22/4RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1Hydrogen iodide, HI, is a colourless gas at room temperature.
(a) (i)Explain why HI has a higher boiling point than HCl and HBr.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)The bar chart shows the boiling points of HCl, HBr and HI. The boiling point of HF is not
shown.
300
280
260
boiling 240
point / K 220
200
180
160
HF
HCl
HBr
HI
Hydrogen bonds form between HF molecules.
Draw a bar on the bar chart to predict the boiling point of HF.
Explain your answer.
..............................................................................................................................................
........................................................................................................................................ [2]
(b)The standard enthalpy change of formation,
, of HI(g) is +26.5 kJ mol–1.
Define the term standard enthalpy change of formation.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
9701/22/O/N/21
3
(c)HI(g) can be formed by reacting H2(g) with I2(g). The reaction is reversible, and an equilibrium
forms quickly at high temperatures.
H2(g) + I2(g)
2HI(g)
(i)Construct an expression for the equilibrium constant, Kp, for the reaction of H2(g) and I2(g)
to form HI(g).
Kp =
[1]
(ii)The equilibrium partial pressures of the gases at 200 °C are as follows.
pH2(g) = 895 Pa
pI2(g) = 895 Pa
pHI(g) = 4800 Pa
Calculate Kp for this reaction.
Kp = .............................. [1]
(iii)State how the value of Kp would change, if at all, if the reaction were carried out at 100 °C
rather than 200 °C.
Explain your answer.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/22/O/N/21
[Turn over
4
(d)HI reacts with oxygen to form iodine and water.
(i)Construct an equation for the reaction of HI with oxygen.
........................................................................................................................................ [1]
(ii)Explain, with reference to oxidation numbers, why this reaction is a redox reaction.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(e)HI(g) can also be formed by the reaction of I2(g) with hydrazine, N2H4(g).
2I2(g) + N2H4(g) → 4HI(g) + N2(g)
State the change in pressure that would occur when 2 mol I2(g) fully reacts with 1 mol N2H4(g)
in a sealed container at constant temperature. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
9701/22/O/N/21
5
(f)In the laboratory, HI(aq) can be formed in a two-step process.
step 1
3I2(s) + 2P(s) → 2PI3(s)
step 2
PI3(s) + 3H2O(l) → H3PO3(aq) + 3HI(aq)
(i)Draw a ‘dot-and-cross’ diagram of a PI3 molecule.
[2]
(ii)Name the type of reaction in step 2.
........................................................................................................................................ [1]
(iii)H3PO3(aq) and HI(aq) are both strong Brønsted–Lowry acids.
Give the meaning of the term strong Brønsted–Lowry acid.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iv)Give the formula of the conjugate base of H3PO3.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/O/N/21
[Turn over
6
(g)HI(g) reacts with propene, CH3CH=CH2(g) to form a mixture of 1-iodopropane and
2-iodopropane.
(i)Identify which of 1-iodopropane and 2-iodopropane is the major product of this reaction.
Explain your answer.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Complete the diagram to show the mechanism of the reaction between HI and CH3CH=CH2
that forms the major product identified in (g)(i).
Include curly arrows, lone pairs of electrons and charges as necessary.
H 3C
H
C
C
H
H
H
+
I
–
[3]
© UCLES 2021
[Total: 26]
9701/22/O/N/21
7
2
(a)Table 1 gives physical data for some of the Period 3 elements.
Table 1
atomic number, Z
11
bonding present in element
M
first ionisation energy / kJ mol–1
494
12
13
14
15
16
C
736
577
786
1060
1000
maximum oxidation number
anionic radius / nm
17
1260
+7
–
–
–
0.271
0.212
0.184
0.181
(i)Complete the row in the table labelled ‘bonding present in element’.
Use C = covalent, I = ionic, M = metallic, as appropriate.
(ii)
[1]
xplain the difference between the first ionisation energies of the elements with atomic
E
numbers 11 and 17.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)
xplain the difference between the first ionisation energies of the elements with atomic
E
numbers 15 and 16.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iv)Complete the row in the table labelled ‘maximum oxidation number’.
[1]
(v)Explain the variation in anionic radius for the elements with atomic numbers 14 to 17.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/22/O/N/21
[Turn over
8
(b)Use the axes to sketch a graph that shows the trend in melting points of the elements with
atomic numbers 11 to 17.
melting point
of element
11
12
13
14
15
16
17
atomic number, Z
[2]
(c) Dmitri Mendeleev published the first Periodic Table in 1869.
Mendeleev used his knowledge of chemical periodicity to propose the properties of gallium,
31Ga, a Group 13 element.
Table 2 gives some chemical and physical data of elements in Group 13.
Table 2
element
density
/ g cm–3
boiling point
/K
cationic radius
/ nm
B
2.34
3930
0.020
2470
0.050
5
13
31
Al
Ga
5.91
In
7.30
Tl
11.8
49
81
2400
0.081
1460
Complete the table by predicting values for the missing data.
© UCLES 2021
9701/22/O/N/21
0.095
[3]
9
(d)Indium and aluminium are elements in Group 13 of the Periodic Table.
Indium has very similar chemical properties to aluminium.
●
●
●
Indium reacts vigorously with hydrochloric acid to form a colourless gas and a salt in
solution.
Indium oxide, In2O3, is amphoteric.
Gaseous indium bromide has the formula In2Br6. This molecule contains coordinate bonds.
(i)Identify the formula of the salt formed when indium reacts with hydrochloric acid.
........................................................................................................................................ [1]
(ii)Construct an equation for the reaction of In2O3 with excess aqueous NaOH.
........................................................................................................................................ [1]
(iii)Draw a diagram that clearly shows the types of bond present in In2Br6(g).
[2]
© UCLES 2021
[Total: 17]
9701/22/O/N/21
[Turn over
10
3Compound T is an isomer of C6H12.
T
(a)Name T.
............................................................................................................................................... [1]
(b)
Draw the skeletal formula of a structural isomer of T that shows cis-trans (geometrical)
isomerism.
[1]
(c)Each carbon atom in T forms a sigma (σ) bond to at least one other carbon atom, as shown.
H 3C
C
H3C
C
CH3
CH3
(i)On the diagram, draw the orbitals that represent the pi (π) bond that is also present in T.
[1]
(ii)State the hybridisation of the two carbon atoms between which the pi (π) bond forms.
........................................................................................................................................ [1]
(d)A reaction scheme starting with T is shown. Reaction 2 occurs in the presence of a catalyst;
knowledge of the mechanism for this reaction is not required.
T
U
reaction 1
HO
V
OH
reaction 2
catalyst
O
(i)Give the reagent(s) and conditions for reaction 1.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/O/N/21
11
(ii)State and explain how 2,4-dinitrophenylhydrazine (2,4-DNPH) can be used to detect the
presence of V as a product of reaction 2.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)The progress of reaction 2 can be monitored by infrared spectroscopy.
The absorption caused by O–H bonds is always present because water is used as a
solvent.
Identify two absorptions, and the bonds responsible for these absorptions, whose
appearance will change significantly during the reaction.
1 ...........................................................................................................................................
..............................................................................................................................................
2 ...........................................................................................................................................
..............................................................................................................................................
[2]
(e)
V is used in a wide range of organic reactions.
Some reactions of V are shown.
W
V
O
reaction 3
O
alkaline
aqueous I2
O–
reaction 4 NaBH4
X
Y
OH
reaction 5
reaction 6
dehydration
addition
polymerisation
Z
(i)
V and W are colourless and soluble in water.
State what you would observe in reaction 3.
........................................................................................................................................ [1]
© UCLES 2021
9701/22/O/N/21
[Turn over
12
(ii)Reaction 3 is a redox reaction.
Identify which of the reactants is reduced in this reaction.
........................................................................................................................................ [1]
(iii)Construct an equation for reaction 4.
Use [H] in the equation to represent an atom of hydrogen from NaBH4.
C6H12O + ��������������������������������������������������������������������������������������������������������������������� [1]
(iv)
X is a mixture of two optical isomers.
Draw the two optical isomers in the boxes provided.
[2]
(v)Both optical isomers of X can be dehydrated to form a single product, Y.
Give the reagent(s) and conditions required for reaction 5.
........................................................................................................................................ [1]
(vi)
Y can form an addition polymer Z.
Draw one repeat unit of Z.
[1]
(vii)Reaction 6 does not proceed quickly at room temperature.
Suggest why this is the case.
..............................................................................................................................................
........................................................................................................................................ [1]
[Total: 17]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.
Cambridge Assessment International Education is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of
Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge.
© UCLES 2021
9701/22/O/N/21
Cambridge International AS & A Level
*3278707654*
CHEMISTRY9701/23
Paper 2 AS Level Structured Questions
October/November 2021
1 hour 15 minutes
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 60.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 16 pages. Any blank pages are indicated.
IB21 11_9701_23/6RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1
Sulfides are compounds that contain sulfur but not oxygen.
(a) Carbon disulfide, CS2, is a volatile liquid at room temperature and pressure.
(i)
State the meaning of volatile.
........................................................................................................................................ [1]
(ii)
Draw a ‘dot-and-cross’ diagram of the CS2 molecule.
[2]
(iii)
Suggest the bond angle in a molecule of CS2.
........................................................................................................................................ [1]
(iv)CS2 is a liquid under room conditions, while CO2 is a gas.
Explain what causes the difference in the physical properties between CS2 and CO2.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/23/O/N/21
3
(b) The enthalpy change of combustion of CS2(l) is represented by the following equation.
CS2(l) + 3O2(g) (i)
∆Hc
CO2(g) + 2SO2(g)
Define enthalpy change of combustion.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)
The table shows the enthalpy changes of formation of CS2(l), CO2(g) and SO2(g).
compound
enthalpy change of
formation, ∆Hf / kJ mol–1
CS2(l)
+89.7
CO2(g)
–394
SO2(g)
–297
se the data in the table to calculate the enthalpy change of combustion, ∆Hc, of CS2(l), in
U
kJ mol–1.
Show your working.
∆Hc of CS2(l) = .............................. kJ mol–1
[2]
© UCLES 2021
9701/23/O/N/21
[Turn over
4
(c) H
ydrogen sulfide gas, H2S(g), is slightly soluble in water. It acts as a weak acid in aqueous
solution.
(i)
State the meaning of weak acid.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Give the formula of the conjugate base of H2S.
........................................................................................................................................ [1]
(iii)H2S(aq) reacts slowly with oxygen dissolved in water. The reaction is represented by the
following equation.
H2S(aq) + 12 O2(aq) → H2O(l) + S(s)
Explain, with reference to oxidation numbers, why this reaction is a redox reaction.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
9701/23/O/N/21
5
(d) The compound As2S3 is a common mineral.
When As2S3 is heated strongly in air, it forms a mixture of products, as shown.
2As2S3(s) + 9O2(g) → As4O6(s) + 6SO2(g)
(i)
sample containing 0.198 g As2S3 is placed in 0.100 dm3 of pure oxygen, an excess, in a
A
reaction chamber connected to a gas syringe at room temperature.
he reactants are heated until no further change is observed. The products are then
T
allowed to cool to room temperature.
Calculate the volume, in dm3, of gas present at the end of the experiment.
he molar volume of gas is 24.0 dm3 mol–1 under these conditions. Assume that the
T
pressure is constant throughout the experiment.
Show your working.
volume of gas remaining = ............................. dm3
[4]
(ii)
State the environmental consequences of releasing SO2(g) into the atmosphere.
........................................................................................................................................ [1]
(iii)
SO2(g) can be removed from the air by reacting it with NaOH(aq).
Construct an equation for the reaction of SO2(g) with NaOH(aq). Include state symbols.
........................................................................................................................................ [2]
© UCLES 2021
[Total: 21]
9701/23/O/N/21
[Turn over
6
2
The reaction scheme shows some reactions of calcium.
Ca(s)
reaction 1
HNO3
Ca(NO3)2(aq)
NaOH(aq)
heat
reaction 2 CO2(g)
CaO(s)
reaction 4 C(s)
CaC2(s)
(a) (i)
Ca(OH)2(aq)
CaCO3(s) + H2O(l)
reaction 3 excess CO2(g)
Ca(HCO3)2(aq)
Reaction 1 produces Ca(NO3)2 and one other product.
Identify the other product.
........................................................................................................................................ [1]
(ii)
Construct an equation for the thermal decomposition of Ca(NO3)2(s).
........................................................................................................................................ [1]
(iii)
State the trend in the thermal stability of the Group 2 nitrates down the group.
........................................................................................................................................ [1]
(iv)
In reaction 3, excess CO2 is bubbled through water containing CaCO3. A solution of
Ca(HCO3)2(aq) forms.
Construct an equation for reaction 3.
........................................................................................................................................ [1]
(b) Describe how Ca(OH)2 is used in agriculture.
.....................................................................................................................................................
............................................................................................................................................... [1]
© UCLES 2021
9701/23/O/N/21
7
(c) In reaction 4, calcium carbide, CaC2, is formed from CaO.
CaC2 contains the C22– anion. Each carbon in C22– is sp hybridised.
(i)
Describe how sp hybridised orbitals are formed.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Sketch a diagram to show how two sp hybrid orbitals can form a sigma (σ) bond.
[2]
© UCLES 2021
9701/23/O/N/21
[Turn over
8
(d) The flowchart shows some reactions of CaC2.
CaC2
N2
CaCN2
reaction 5
H 2O
CaCO3 + NH3
NaCl and C
NaCN
(i)
Reaction 5 can be used to prepare NH3.
CaCN2 + 3H2O → CaCO3 + 2NH3
alculate the minimum mass, in tonnes, of calcium cyanamide, CaCN2, that is required to
C
produce 1.50 × 106 tonnes of NH3.
Show your working.
1 tonne = 1.00 × 106 g
minimum mass of CaCN2 = .............................. tonnes
[2]
(ii)
CH3CH2Br
O
Draw the structure of the organic products formed in the following reactions.
H2SO4(aq)
NaCN
dissolved
in ethanol
heat under
reflux
NaCN
and HCN
[3]
© UCLES 2021
[Total: 13]
9701/23/O/N/21
9
3
Phosphorus is a reactive Period 3 element.
(a) Phosphorus has several allotropes. Details of two allotropes are given.
(i)
allotrope of phosphorus
formula
melting point / °C
white
P4
44
red
P
590
White phosphorus and red phosphorus both have covalent bonding.
Suggest the types of structure shown by white phosphorus (P4) and red phosphorus (P).
Explain why red phosphorus (P) has a higher melting point than white phosphorus (P4).
structure of P4 ......................................................................................................................
structure of P .......................................................................................................................
explanation ..........................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
[3]
(ii)
Red phosphorus (P) forms when white phosphorus (P4) is exposed to sunlight.
1
4 P4(s)
→ P(s)
white
red
∆H = –17.6 kJ mol–1
Use this information to draw a reaction pathway diagram to show the formation of red
phosphorus (P) from white phosphorus (P4).
enthalpy
P4
progress of reaction
[1]
© UCLES 2021
9701/23/O/N/21
[Turn over
10
(b) Some reactions of P4(s) are shown in the reaction scheme.
P4(s)
excess Cl 2(g)
H2O(l)
excess O2(g)
P4O10(s)
(i)
PCl 5(s)
reaction 2
H2O(l)
reaction 1
Q
State the oxidation number of phosphorus in P4O10.
........................................................................................................................................ [1]
(ii)
Deduce the identity of Q and hence construct chemical equations for reactions 1 and 2.
reaction 1
PCl 5 + .......H2O → ...............................................................................................
reaction 2 P4O10 + .......H2O → ..............................................................................................
[2]
(c) Triphenylphosphine is used in a type of reaction known as a Wittig reaction.
triphenylphosphine
P
(i)
where
= –C6H5
Give the empirical formula of triphenylphosphine.
........................................................................................................................................ [1]
© UCLES 2021
9701/23/O/N/21
11
In a Wittig reaction, an aldehyde reacts with a halogenoalkane to form an alkene. The conversion
is shown in the following unbalanced equation.
O
R
1
H
+
I
R2
R2
triphenylphosphine
strong base
R1
H
Compound H can be made from propanal, C2H5CHO. Stage 3 in the reaction scheme is a
Wittig reaction.
stage 1
C2H5CHO
stage 2
G
stage 3
(Wittig reaction)
(ii)
C2H5CH2I + C2H5CHO
NaBH4
G
red phosphorus and I2
triphenylphosphine
strong base
C2H5CH2I
H
State the types of reaction that occur in stages 1 and 2.
stage 1 .................................................................................................................................
stage 2 .................................................................................................................................
[2]
(iii)
Draw the structures of G and H in the boxes provided.
G
H
[2]
(d) Identify the organic products formed when compound J, shown below, is heated with hot
concentrated acidified manganate(VII) ions.
J
hot concentrated MnO4–
H2SO4
[2]
© UCLES 2021
[Total: 14]
9701/23/O/N/21
[Turn over
12
4
Compound B is a liquid with a fruity smell.
B
O
Br
O
The reaction scheme shows how B can be made from ethanol, C2H5OH.
C2H5OH
O
reaction 1
[O]
O
reaction 2
HO
Br
HO
C2H5OH
and H2SO4
reaction 3
B
O
O
(a) (i)
Br
Reaction 1 is an oxidation reaction.
Give the reagent(s) and conditions required for reaction 1.
reagent(s) ............................................................................................................................
conditions ............................................................................................................................
..............................................................................................................................................
[2]
(ii)Construct an equation to represent reaction 1.
Use [O] to represent an oxygen atom from the oxidising agent in this reaction.
........................................................................................................................................ [1]
(iii)
Suggest the type of reaction that occurs in reaction 2.
........................................................................................................................................ [1]
(iv)H2SO4 acts as a homogeneous catalyst in reaction 3.
Explain why H2SO4 is described as homogeneous.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/23/O/N/21
13
(b) Reaction 2 needs to take place in the absence of water to prevent formation of compound C.
C
O
HO
OH
If C is present in the reaction mixture of reaction 3, a different compound, compound D, will
also form. Compound D has two identical functional groups.
he infrared spectrum of D shows strong absorptions at 1100 cm–1 and 1720 cm–1, but no
T
absorption due to O–H bonds.
Use the Data Booklet to identify the functional group present in D.
Explain your answer as fully as you can.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
© UCLES 2021
9701/23/O/N/21
[Turn over
14
(c) Some other reactions of C are shown.
C
O
HO
OH
Na2CO3
E
(i)
F
(CH2OH)2
SOCl 2
G
(CH2Cl )2
Draw the structure of E.
[1]
(ii)
Suggest why NaBH4 is not a suitable reagent to make F, (CH2OH)2, from C.
xplain your answer.
E
..............................................................................................................................................
........................................................................................................................................ [1]
(iii)
Construct an equation for the reaction of (CH2OH)2 with SOCl 2 to form G, (CH2Cl )2.
........................................................................................................................................ [1]
(d) Explain why C is very soluble in water.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [1]
© UCLES 2021
[Total: 12]
9701/23/O/N/21
Cambridge International AS & A Level
*0300697260*
CHEMISTRY9701/41
Paper 4 A Level Structured Questions
October/November 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 20 pages. Any blank pages are indicated.
IB21 11_9701_41/FP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1When dilute sulfuric acid is electrolysed, water is split into hydrogen and oxygen.
2H2O(l) → 2H2(g) + O2(g)
A current of x A is passed through the solution for 14.0 minutes. 462 cm3 of hydrogen are produced
at the cathode, measured under room conditions.
(a)Calculate the number of hydrogen molecules produced during the electrolysis.
number of hydrogen molecules = .............................. [2]
(b)
Calculate the total number of electrons transferred to produce this number of hydrogen
molecules.
total number of electrons = .............................. [1]
(c)Calculate the quantity of charge, in coulombs, of the total number of electrons calculated in (b).
quantity of charge = .............................. C [1]
(d)Calculate the current, x, passed during this experiment.
x = .............................. A [1]
© UCLES 2021
9701/41/O/N/21
3
(e)The standard entropies, S o, of three species are given in the table.
species
S o / J K–1 mol–1
H2O(l)
+70
H2(g)
+131
O2(g)
+205
(i)Calculate ∆S o for the reaction 2H2O(l) → 2H2(g) + O2(g).
∆S o = .............................. J K–1 mol–1 [1]
(ii)
∆H o for the reaction 2H2O(l) → 2H2(g) + O2(g) is +572 kJ mol–1.
Calculate ∆G o for this reaction at 298 K.
∆G o = .............................. kJ mol–1 [2]
(iii) Predict the effect of increasing temperature on the spontaneity of this reaction.
Explain your answer.
..............................................................................................................................................
........................................................................................................................................ [1]
[Total: 9]
© UCLES 2021
9701/41/O/N/21
[Turn over
4
2Solution Y is hydrochloric acid, HCl (aq). Solution Z is aqueous 4-chlorobutanoic acid,
Cl (CH2)3CO2H(aq). The pKa of Cl (CH2)3CO2H(aq) is 4.52. The pH of both solutions is 4.00.
(a) (i)Write an expression for the Ka of Cl (CH2)3CO2H(aq).
Ka =
[1]
(ii)Write a mathematical expression to describe the relationship between Ka and pKa.
........................................................................................................................................ [1]
(iii)Calculate [H+] in solutions Y and Z.
[H+] = .............................. mol dm–3 [1]
(iv)Calculate the ratio
[HCl ] dissolved in solution Y
.
[Cl (CH2)3CO2H] dissolved in solution Z
[HCl ] dissolved in solution Y
= .............................. [2]
[Cl (CH2)3CO2H] dissolved in solution Z
(b) A buffer solution of pH 5.00 is produced by adding sodium propanoate to 5.00 g of propanoic acid
in 100 cm3 of distilled water.
alculate the mass of sodium propanoate that must be used to produce this buffer solution.
C
The Ka of propanoic acid is 1.35 × 10–5 mol dm–3.
[Mr: propanoic acid, 74.0; sodium propanoate, 96.0]
© UCLES 2021
mass of sodium propanoate = .............................. g [3]
9701/41/O/N/21
5
(c) S
ome dilute sulfuric acid is mixed with a small sample of the buffer solution described in (b).
The final pH of the mixture is close to 1.
Explain this observation.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
[Total: 10]
© UCLES 2021
9701/41/O/N/21
[Turn over
6
3
(a) Define the term electron affinity.
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)Write an equation for the process corresponding to the second ionisation energy of calcium.
Include state symbols.
............................................................................................................................................... [1]
Some data relating to calcium and oxygen are listed. Select relevant data from this list for your
answers to parts (c), (d) and (e).
process
value / kJ mol–1
first ionisation energy of oxygen
+1310
second ionisation energy of oxygen
+3390
first electron affinity of oxygen
–142
second electron affinity of oxygen
+844
enthalpy change for 12 O2(g) + 2e– → O2–(g)
+951
enthalpy change for Ca(s) → Ca2+(g) + 2e–
+1933
lattice energy of CaO(s)
–3517
(c)Oxygen exists as O2 molecules.
Use the data in this question to calculate a value for the bond energy of the O=O bond.
Show all your working.
© UCLES 2021
bond energy = .............................. kJ mol–1 [3]
9701/41/O/N/21
7
(d) (i)
Suggest why the first electron affinity of oxygen is negative.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Suggest why the second electron affinity of oxygen is positive.
..............................................................................................................................................
........................................................................................................................................ [1]
(e)Calculate the enthalpy of formation of calcium oxide, CaO(s).
enthalpy of formation = .............................. kJ mol–1 [2]
(f) The lattice energy of lithium fluoride, LiF(s), is –1022 kJ mol–1.
Identify the factor that causes the lattice energy of calcium oxide to be more exothermic than
that of lithium fluoride. Explain why this factor causes the difference in lattice energies.
.....................................................................................................................................................
............................................................................................................................................... [2]
[Total: 12]
© UCLES 2021
9701/41/O/N/21
[Turn over
8
4Separate samples of 0.02 mol of calcium carbonate and 0.02 mol of barium carbonate are heated
until completely decomposed to the metal oxide and carbon dioxide.
(a)State which of these two Group 2 carbonates requires the higher temperature before it begins
to decompose. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)After decomposition is complete, the 0.02 mol sample of calcium oxide is taken and added to
2.00 dm3 of water. A solution is formed with no solid present. Dilute sulfuric acid is then added
dropwise until a precipitate is seen.
The same procedure is repeated with the 0.02 mol sample of barium oxide, using the same
concentration solution of dilute sulfuric acid.
Identify the sample to which most sulfuric acid must be added to cause a precipitate to appear.
Explain your answer. You should refer to the solubilities of the precipitates and relevant energy
terms in your answer.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(c) (i)Calculate the mass, in g, of CO2 produced by the decomposition of 0.020 moles of
calcium carbonate.
mass of CO2 = .............................. g [1]
(ii)Calculate the minimum mass, in g, of propane that would, on complete combustion,
produce the same mass of CO2 calculated in (c)(i).
Give your answer to three significant figures.
mass of propane = .............................. g [2]
[Total: 8]
© UCLES 2021
9701/41/O/N/21
9
5
(a)[MnCl 4]2– is a complex ion.
(i)Deduce the oxidation state of manganese in [MnCl 4]2–.
oxidation state = .............................. [1]
(ii)The [MnCl 4]2– complex does not contain any 180° bond angles.
Draw a three-dimensional diagram to show the shape of the [MnCl 4]2– complex.
State one bond angle on your diagram.
Mn
[2]
(b)A solution of cobalt(II) sulfate contains the complex ion [Co(H2O)6]2+.
A solution containing [Co(H2O)6]2+ is reacted separately with an excess of each of NaOH(aq),
NH3(aq) and NaCl (aq).
Write an equation for each of these reactions. State one observation that can be made
immediately after the reaction, include the colour and state of the cobalt-containing product.
(i)[Co(H2O)6]2+ and an excess of NaOH(aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
(ii)[Co(H2O)6]2+ and an excess of NH3(aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
© UCLES 2021
9701/41/O/N/21
[Turn over
10
(iii)[Co(H2O)6]2+ and an excess of NaCl (aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
(iv)Name the type of reaction that occurs in (b)(iii).
........................................................................................................................................ [1]
(c)Cobalt forms the complex ion [Co(NH3)2(en)2]2+. The abbreviation en is used for the bidentate
ligand 1,2-diaminoethane, H2NCH2CH2NH2. The complex ion shows both geometrical and
optical isomerism.
(i)
Define the term bidentate ligand.
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw three-dimensional diagrams for the two optical isomers of [Co(NH3)2(en)2]2+.
Each en ligand can be represented using
N
Co
N
.
Co
[2]
© UCLES 2021
[Total: 14]
9701/41/O/N/21
11
6An excess of sodium iodide is added to a solution of copper(II) sulfate. Iodine and a white precipitate
of copper(I) iodide are formed.
(a)Write an equation for the reaction that occurs.
............................................................................................................................................... [1]
(b) (i)Explain why the copper(II) sulfate solution is coloured.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [4]
(ii)Suggest why the precipitate of copper(I) iodide is white.
..............................................................................................................................................
........................................................................................................................................ [1]
(c)Use suitable E o values from the Data Booklet to predict whether iodide ions can reduce Cu2+
to Cu+ under standard conditions. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(d)An excess of sodium iodide is added to copper(II) sulfate solution. Copper(I) iodide forms as
a precipitate. After precipitation, [Cu+] is much lower than 1.0 mol dm–3.
Use this information and your answer to (c) to explain how the relevant electrode potentials
change and hence why I– ions can reduce Cu2+ ions.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 10]
9701/41/O/N/21
[Turn over
12
7The structure of phenylethanoic acid is shown.
OH
O
(a) G
ive the number of different peaks in the carbon-13 (13C) NMR spectrum of phenylethanoic
acid.
number of peaks = .............................. [1]
(b)Phenylethanoic acid, ethanol and phenol can all behave as acids.
Compare and explain the relative acidities of these three compounds.
............................................ > ............................................ > ............................................
most acidic
least acidic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(c)Phenylethanoic acid can be synthesised using benzene as the starting material.
In the first stage of this synthesis, benzene reacts with chloromethane in the presence of an
Al Cl 3 catalyst to form methylbenzene.
Chloromethane reacts with Al Cl 3 to form two ions. One of these is the carbocation +CH3.
(i)Write an equation for the reaction between chloromethane and Al Cl 3.
........................................................................................................................................ [1]
(ii)Draw the mechanism of the reaction between benzene and +CH3. Include all relevant curly
arrows, charges and the structure of the intermediate.
intermediate
CH3
+
CH3
[3]
© UCLES 2021
9701/41/O/N/21
13
(d)A three-step synthesis of phenylethanoic acid from methylbenzene is shown.
Br
step 1
step 2
compound
Q
OH
step 3
O
(i)State reagents and conditions for step 1.
........................................................................................................................................ [1]
(ii)Suggest the structure of compound Q.
[1]
(iii)State reagents and conditions for steps 2 and 3.
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
[2]
(iv)Draw the structure of an organic by-product that forms in step 1.
[1]
© UCLES 2021
[Total: 14]
9701/41/O/N/21
[Turn over
14
8Phenylamine, C6H5NH2, and ethylamine, C2H5NH2, can be distinguished by adding aqueous
bromine.
(a)State what is seen when aqueous bromine is added to phenylamine.
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)Suggest what is seen when aqueous bromine is added to ethylamine.
............................................................................................................................................... [1]
(c)Draw the structure of the organic product formed when an excess of aqueous bromine is
added to phenylamine.
[1]
(d)Name the product you have drawn in (c).
............................................................................................................................................... [1]
© UCLES 2021
[Total: 5]
9701/41/O/N/21
15
9Compound T is made by a three-stage synthesis.
(a)In stage 1, phenylethanoic acid reacts with a suitable reagent to form compound R.
R
phenylethanoic acid
OH
stage 1
Cl
O
O
Suggest a suitable reagent for stage 1.
............................................................................................................................................... [1]
(b)In stage 2, compound R reacts with ethylamine to form compound S.
R
S
H
Cl
stage 2
N
+ C2H5NH2 O
O
(i)Name the functional group formed in stage 2.
........................................................................................................................................ [1]
(ii)Identify the other product formed in stage 2.
........................................................................................................................................ [1]
(c)In stage 3, compound S reacts with a suitable reagent to form compound T.
S
T
H
N
stage 3
H
N
O
(i)State the formula of a suitable reagent for stage 3.
........................................................................................................................................ [1]
(ii)Name the type of reaction that occurs in stage 3.
........................................................................................................................................ [1]
© UCLES 2021
9701/41/O/N/21
[Turn over
16
(d)The relative abundance of the molecular ion peak in the mass spectrum of ethylamine is 62.
(i)Calculate the relative abundance of the M+1 peak in the mass spectrum of ethylamine.
relative abundance = .............................. [1]
(ii)The mass spectrum of compound T contains several fragments. The m/e values of two of
these fragments are 29 and 91.
Draw the structures of the ions responsible for these peaks.
structure of ion
m/e
29
91
[2]
(e)The proton (1H) NMR spectrum of compound T shows hydrogen atoms in different environments.
Six of these environments are shown on the structure using letters a, b, c, d, e and f.
H d
b
N
c
f
e
a
Use the letters a, b, c, d, e and f to answer the questions that follow. The questions relate to
the proton (1H) NMR spectrum of T.
Proton d does not cause splitting of the peaks for protons c or e under the conditions used.
Each answer may be one, or more than one, of the letters a, b, c, d, e and f.
(i)Identify the proton or protons with a chemical shift (δ) in the range 6.0 to 9.0.
.............................. [1]
(ii)Identify the proton or protons whose peak will disappear if D2O is added.
© UCLES 2021
.............................. [1]
9701/41/O/N/21
17
(iii)Identify the proton or protons whose peak is a triplet.
.............................. [1]
(iv)Identify the proton or protons with the lowest chemical shift (δ).
.............................. [1]
[Total: 12]
© UCLES 2021
9701/41/O/N/21
[Turn over
18
10 V
aline (Val) and lysine (Lys) are amino acids. The structures of these amino acids can be found in
the Data Booklet.
The isoelectric point of an amino acid is the pH at which it exists as a zwitterion. The isoelectric
point of valine is 6.0. The isoelectric point of lysine is 9.7.
(a)Draw the structure of valine at pH 6.0.
[1]
(b)A solution of lysine is produced with pH 9.7. Dilute sulfuric acid is added slowly until the pH of
the solution is 1.0. The sulfuric acid reacts with lysine to produce different organic ions that are
not present in significant concentrations at pH 9.7.
Draw the structures of three of the organic ions that form during the addition of sulfuric acid in
the boxes. Draw the organic ion present at pH 1.0 in box C.
A
B
C (pH 1.0)
[3]
(c) Draw the structure of the dipeptide Val-Lys. The peptide bond should be shown fully displayed.
[2]
© UCLES 2021
[Total: 6]
9701/41/O/N/21
Cambridge International AS & A Level
*3952457672*
CHEMISTRY9701/42
Paper 4 A Level Structured Questions
October/November 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 20 pages. Any blank pages are indicated.
IB21 11_9701_42/4RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1Radium is a Group 2 element.
The predicted lattice energy,
(a)Define
, of radium sulfide, RaS, is –2612 kJ mol–1.
.
.....................................................................................................................................................
............................................................................................................................................... [2]
Some data relating to radium and sulfur are listed. Select relevant data from this list for use in your
answers to parts (b) to (e).
process
value / kJ mol–1
enthalpy change for Ra(s) → Ra2+(g) + 2e–
+1619
first ionisation energy of sulfur
+1000
second ionisation energy of sulfur
+2260
first electron affinity of sulfur
–200
second electron affinity of sulfur
+532
enthalpy change for
S8(s) + 2e– → S2–(g)
lattice energy of RaS(s)
+555
–2612
(b)Write an equation for the process corresponding to the second electron affinity of sulfur.
Include state symbols.
............................................................................................................................................... [1]
(c)Sulfur exists as S8 molecules in the solid state.
Use the data in this question to calculate the enthalpy change for the reaction S8(s) → 8S(g).
© UCLES 2021
enthalpy change = .............................. kJ mol–1 [3]
9701/42/O/N/21
3
(d)Calculate the standard enthalpy change of formation,
standard enthalpy change,
, of radium sulfide.
= .............................. kJ mol–1 [2]
(e) (i)State the two major factors that affect the numerical magnitude of a lattice energy.
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)For each factor you have identified in (e)(i), state whether it tends to make the lattice
energy of radium sulfide more or less exothermic than that of sodium chloride.
Explain your answer.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
(iii)The lattice energies of sodium chloride, NaCl, and radium sulfide, RaS, are –771 kJ mol–1
and –2612 kJ mol–1, respectively.
Identify the dominant factor in determining the relative numerical magnitudes of the lattice
energies of radium sulfide and sodium chloride.
Explain your answer.
..............................................................................................................................................
........................................................................................................................................ [1]
[Total: 13]
© UCLES 2021
9701/42/O/N/21
[Turn over
4
2Ethoxyethane, C2H5OC2H5, can dissolve both in water and in octan-1-ol. The expression and
numerical value for the partition coefficient of ethoxyethane between water and octan-1-ol are
given. Water and octan-1-ol are immiscible.
Kpc =
concentration of C2H5OC2H5 in octan-1-ol
= 6.760 at 20 °C
concentration of C2H5OC2H5 in water
(a)In an experiment, octan-1-ol at 20 °C is added to a solution of ethoxyethane in water at 20 °C.
The mixture is analysed immediately and a value of Kpc is calculated.
The calculation is performed correctly; the value calculated is 5.625.
Explain why the value calculated is less than 6.760.
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)A second experiment is performed and the value of Kpc is found to be 6.760. The concentration
of ethoxyethane in the octan-1-ol layer is 7.62 g dm–3.
(i)Calculate the concentration, in g dm–3, of ethoxyethane in the aqueous layer.
.............................. g dm–3 [1]
(ii)100 cm3 of the octan-1-ol layer is taken and shaken with 100 cm3 of water.
Calculate the maximum amount, in mol, of ethoxyethane that can be extracted into the
water.
© UCLES 2021
.............................. mol [3]
9701/42/O/N/21
5
(c)An aqueous solution of lead(II) nitrate is mixed with an aqueous solution of sodium iodide. A
yellow precipitate of lead(II) iodide is formed and is filtered out, leaving solution X.
The concentration of Pb2+ in solution X is 5.68 × 10–3 mol dm–3.
The concentration of I– in solution X is 4.20 × 10–4 mol dm–3.
(i)Use these data to calculate a value for the solubility product, Ksp, of lead(II) iodide.
State the units of Ksp.
Ksp = ..............................
units = ..............................
[2]
(ii)Potassium iodide is very soluble in water.
Describe and explain what is seen if a few drops of saturated potassium iodide solution
are added to a portion of solution X.
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
[Total: 10]
© UCLES 2021
9701/42/O/N/21
[Turn over
6
3Pure water is a very poor conductor of electricity. However, when hydrogen chloride gas is dissolved
in water, ions are formed and a current flows during electrolysis.
HCl (g) + aq → H+(aq) + Cl –(aq)
The overall change after electrolysis is that hydrogen chloride gas is converted into hydrogen and
chlorine.
2HCl (g) → H2(g) + Cl 2(g)
When a current of 3.10 A is passed through the solution for Y minutes, 351 cm3 of chlorine are
produced at the anode, measured under room conditions.
(a)Calculate the number of chlorine molecules produced during the electrolysis.
number of chlorine molecules = .............................. [2]
(b)Calculate the total number of electrons transferred to produce this number of chlorine molecules.
total number of electrons = .............................. [1]
(c)Calculate the quantity of charge, in coulombs, of the total number of electrons calculated in (b).
quantity of charge = .............................. C [1]
(d)Calculate the time, Y, in minutes, for which the current flows.
© UCLES 2021
Y = .............................. minutes [1]
9701/42/O/N/21
7
(e)The standard entropies, S o, of three species are given in the table.
species
S o / J K–1 mol–1
HCl (g)
+187
H2(g)
+131
Cl 2(g)
+223
(i)Calculate ∆S o for the reaction 2HCl (g) → H2(g) + Cl 2(g).
∆S o = .............................. J K–1 mol–1 [1]
(ii)
∆H o for the reaction 2HCl (g) → H2(g) + Cl 2(g) is +185 kJ mol–1.
Calculate ∆G o for this reaction at 298 K.
∆G o = .............................. kJ mol–1 [2]
(iii)Predict the effect of increasing temperature on the spontaneity of this reaction. Explain
your answer.
..............................................................................................................................................
........................................................................................................................................ [1]
[Total: 9]
© UCLES 2021
9701/42/O/N/21
[Turn over
8
4Separate samples of 0.01 mol of magnesium nitrate and 0.01 mol of strontium nitrate are heated
until completely decomposed to the metal oxide, nitrogen dioxide and oxygen.
(a)State which of these two Group 2 nitrates requires the higher temperature before it begins to
decompose. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)After decomposition is complete the 0.01 mol sample of magnesium oxide is taken and
increasing amounts of water are added to it, with stirring, until no solid remains.
This procedure is repeated with the 0.01 mol sample of strontium oxide.
Identify the sample to which most water must be added to cause all the solid to dissolve.
Explain your answer by reference to the solubilities of the products formed when water is
added to the oxides. You should refer to relevant energy terms in your answer.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(c)The nitrogen dioxide given off by the decomposition of 0.0100 mol of strontium nitrate is
dissolved in water. The oxidising agent H2O2(aq) is then added to give 150.0 cm3 of a solution
in which nitric acid, HNO3, is the only nitrogen-containing product.
(i)Calculate the concentration, in mol dm–3, of HNO3 in the 150.0 cm3 of solution.
© UCLES 2021
concentration = .............................. mol dm–3 [1]
9701/42/O/N/21
9
(ii)The HNO3 present in 25.0 cm3 of this solution is neutralised using 0.125 mol dm–3 NaOH(aq).
Calculate the minimum volume, in cm3, of NaOH(aq) needed. Give your answer to three
significant figures.
volume = .............................. cm3 [1]
[Total: 7]
© UCLES 2021
9701/42/O/N/21
[Turn over
10
5Transition elements form complexes.
(a)Molybdenum, Mo, forms an octahedral complex consisting of one Mo atom surrounded by
carbon monoxide, CO, molecules. CO is a monodentate ligand. Iron forms an octahedral
complex consisting of one Fe3+ and a number of cyanide, CN–, ions. CN– is a monodentate
ligand.
(i)Define the term monodentate ligand.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)Complete the table by stating the formulae and charges of the complexes described.
formula
charge
molybdenum complex
iron(III) complex
[2]
(iii)Draw a three-dimensional diagram to show the shape of this iron(III) complex.
Label one 180° bond angle on your diagram.
Fe
[1]
(b)An excess of aqueous ammonia is added to dilute copper(II) sulfate solution. A dark blue
complex, [Cu(NH3)4(H2O)2]2+, is formed.
(i)Write an ionic equation for this reaction.
........................................................................................................................................ [1]
© UCLES 2021
9701/42/O/N/21
11
(ii)Explain the origin of colour in copper(II) complexes.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [4]
(c)An excess of concentrated hydrochloric acid is added to the dark blue solution of
[Cu(NH3)4(H2O)2]2+. A new complex, Z, is formed. The colour of the solution changes.
(i)Write an equation for the formation of Z from the solution of [Cu(NH3)4(H2O)2]2+. Include the
formula and charge of Z.
........................................................................................................................................ [2]
(ii)Name the type of reaction when Z forms from [Cu(NH3)4(H2O)2]2+.
........................................................................................................................................ [1]
(iii)State the geometry of Z.
........................................................................................................................................ [1]
(iv)State the colour of a solution of Z.
........................................................................................................................................ [1]
(v)Explain why the colour of a solution of [Cu(NH3)4(H2O)2]2+ is different from the colour of a
solution of Z. You should refer to the energies of the orbitals involved in your answer.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
[Total: 15]
9701/42/O/N/21
[Turn over
12
6An excess of aqueous ammonia is added to a solution containing the complex ion [Co(H2O)6]2+.
[Co(H2O)6]2+ + 6NH3
[Co(NH3)6]2+ + 6H2O
(a)Complete the sentence to describe the colour change that will be seen during this reaction.
The colour changes from ................................................ to ���������������������������������������������� . [1]
(b)Write an expression for the stability constant, Kstab, of [Co(NH3)6]2+.
Kstab =
[1]
(c)The numerical value of Kstab of [Co(NH3)6]2+ is 7.7 × 104.
What deduction about the properties of [Co(NH3)6]2+ and [Co(H2O)6]2+ can be made from this
Kstab value?
............................................................................................................................................... [1]
(d)Oxygen can oxidise [Co(NH3)6]2+ to [Co(NH3)6]3+ under standard conditions in alkaline solutions.
[Co(NH3)6]3+ + e–
[Co(NH3)6]2+
(i)Use this information and the Data Booklet to calculate the
[Co(NH3)6]2+.
E o = +0.10 V
value for this oxidation of
..............................................................................................................................................
..............................................................................................................................................
= .............................. V
[1]
(ii)Write an ionic equation for this oxidation of [Co(NH3)6]2+.
........................................................................................................................................ [1]
(iii)Predict, by selecting suitable data from the Data Booklet, whether oxygen can oxidise
Co2+(aq) in acidic solution, in the absence of ammonia. Explain your answer.
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
[Total: 7]
9701/42/O/N/21
13
7The structure of benzene-1,3-dicarboxylic acid is shown.
benzene-1,3-dicarboxylic acid
O
HO
OH
O
(a)State the empirical formula of benzene-1,3-dicarboxylic acid.
............................................................................................................................................... [1]
(b)Benzene-1,3-dicarboxylic acid is an isomer of benzene-1,4-dicarboxylic acid. These two
isomers can be distinguished by carbon-13 (13C) NMR spectroscopy.
State the number of peaks in the carbon-13 (13C) NMR spectrum of each compound.
benzene-1,3-dicarboxylic acid
benzene-1,4-dicarboxylic acid
[2]
(c)Benzene-1,3-dicarboxylic acid can be made by the two-step synthesis shown below.
benzene-1,3-dicarboxylic acid
compound P
O
compound Q
step 1
C9H8O3
O
step 2
HO
OH
HO
O
(i)Name compound P.
........................................................................................................................................ [1]
(ii)Explain why the major product of this two-step synthesis is benzene-1,3-dicarboxylic acid
and not benzene-1,4-dicarboxylic acid.
..............................................................................................................................................
........................................................................................................................................ [1]
© UCLES 2021
9701/42/O/N/21
[Turn over
14
(iii)The reagents used for step 1 are CH3COCl and Al Cl 3. These reagents give rise to
+
CH3C=O ions which react with compound P.
Name the mechanism of this reaction.
........................................................................................................................................ [1]
+
(iv)
Draw the mechanism of the reaction of CH3C=O ions with compound P. Include all
relevant curly arrows and charges, the structure of the intermediate and the structure of
compound Q.
intermediate
compound Q
+
CH3C=O
O
HO
[3]
(v)Suggest a reagent and conditions to convert compound Q into benzene‑1,3‑dicarboxylic
acid, in step 2.
........................................................................................................................................ [1]
© UCLES 2021
[Total: 10]
9701/42/O/N/21
15
8Alanine, H2NCH(CH3)CO2H, and glutamic acid, H2NCH(CH2CH2CO2H)CO2H, are two naturally
occurring amino acids.
(a)H2NCH(CH3)CO2H exists as two optical isomers.
Draw three-dimensional structures of these two optical isomers.
[2]
(b)The proton (1H) NMR spectrum of either alanine in D2O or glutamic acid in D2O is shown.
9
8
7
6
5
4
3
2
1
0
/ ppm
State whether this is the spectrum of alanine in D2O or the spectrum of glutamic acid in D2O.
Explain your answer by reference to the number of peaks and splitting patterns.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
© UCLES 2021
9701/42/O/N/21
[Turn over
16
(c)The mass spectrum of glutamic acid, H2NCH(CH2CH2CO2H)CO2H, is obtained.
(i)State the m/e value of the molecular ion peak in this spectrum.
........................................................................................................................................ [1]
(ii)The spectrum has peaks with m/e values of 88 and 131.
Draw the structures of the ions responsible for these peaks.
m/e
structure of ion
88
131
[2]
(d)At pH 11 alanine exists as H2NCH(CH3)CO2– ions and glutamic acid exists as
H2NCH(CH2CH2CO2–)CO2– ions. A mixture of alanine and glutamic acid at pH 11 is subjected
to electrophoresis.
(i)State how the mixture can be maintained at pH 11 during electrophoresis.
........................................................................................................................................ [1]
(ii)Draw a fully labelled diagram for the apparatus that would be used to carry out this
electrophoresis. Your diagram should include the position of the mixture of alanine and
glutamic acid at the start of the electrophoresis experiment.
[2]
© UCLES 2021
9701/42/O/N/21
17
(iii)
Identify the electrode that each amino acid travels towards during electrophoresis at pH 11.
alanine .................................................................................................................................
glutamic acid ........................................................................................................................
[1]
(iv)In a particular electrophoresis experiment at pH 11, the glutamic acid travels 3.4 cm.
Alanine travels a shorter distance.
Explain the factors that account for the difference in the distances travelled.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [2]
© UCLES 2021
[Total: 14]
9701/42/O/N/21
[Turn over
18
9Butylamine, CH3CH2CH2CH2NH2, can be synthesised from different organic compounds by using
suitable reagents. Each reaction involves one step.
(a)Complete the table to describe three different syntheses.
● One of the three syntheses should involve a nucleophilic substitution reaction.
● The starting organic compound for each synthesis should contain a different functional
group.
● A different reagent should be used for each synthesis.
starting organic compound
reagent and conditions
[6]
(b)Compare and explain the relative basicities of ammonia, butylamine and phenylamine.
.............................................. > ............................................. > .............................................
most basic
least basic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
[Total: 10]
© UCLES 2021
9701/42/O/N/21
19
10 (a)Complete the table to show the structure of the organic product from each reaction of phenol,
C6H5OH.
reaction
reaction mixture
1
phenol + NaOH(aq)
2
phenol + Na(s)
N
+
N
3
structure of organic product
phenol +
(aq)
+ NaOH, at 4 °C
an excess of phenol +
4
O
O
C
Cl
C
Cl
[4]
(b)Identify two reactions from the table in which ethanol would behave in a similar way to phenol.
............................................................................................................................................... [1]
© UCLES 2021
[Total: 5]
9701/42/O/N/21
[Turn over
Cambridge International AS & A Level
*8339479569*
CHEMISTRY9701/43
Paper 4 A Level Structured Questions
October/November 2021
2 hours
You must answer on the question paper.
You will need:
Data booklet
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working, use appropriate units and use an appropriate number of significant
figures.
INFORMATION
●
The total mark for this paper is 100.
●
The number of marks for each question or part question is shown in brackets [ ].
This document has 20 pages. Any blank pages are indicated.
IB21 11_9701_43/3RP
© UCLES 2021
[Turn over
2
Answer all the questions in the spaces provided.
1When dilute sulfuric acid is electrolysed, water is split into hydrogen and oxygen.
2H2O(l) → 2H2(g) + O2(g)
A current of x A is passed through the solution for 14.0 minutes. 462 cm3 of hydrogen are produced
at the cathode, measured under room conditions.
(a)Calculate the number of hydrogen molecules produced during the electrolysis.
number of hydrogen molecules = .............................. [2]
(b)
Calculate the total number of electrons transferred to produce this number of hydrogen
molecules.
total number of electrons = .............................. [1]
(c)Calculate the quantity of charge, in coulombs, of the total number of electrons calculated in (b).
quantity of charge = .............................. C [1]
(d)Calculate the current, x, passed during this experiment.
x = .............................. A [1]
© UCLES 2021
9701/43/O/N/21
3
(e)The standard entropies, S o, of three species are given in the table.
species
S o / J K–1 mol–1
H2O(l)
+70
H2(g)
+131
O2(g)
+205
(i)Calculate ∆S o for the reaction 2H2O(l) → 2H2(g) + O2(g).
∆S o = .............................. J K–1 mol–1 [1]
(ii)
∆H o for the reaction 2H2O(l) → 2H2(g) + O2(g) is +572 kJ mol–1.
Calculate ∆G o for this reaction at 298 K.
∆G o = .............................. kJ mol–1 [2]
(iii) Predict the effect of increasing temperature on the spontaneity of this reaction.
Explain your answer.
..............................................................................................................................................
........................................................................................................................................ [1]
[Total: 9]
© UCLES 2021
9701/43/O/N/21
[Turn over
4
2Solution Y is hydrochloric acid, HCl (aq). Solution Z is aqueous 4-chlorobutanoic acid,
Cl (CH2)3CO2H(aq). The pKa of Cl (CH2)3CO2H(aq) is 4.52. The pH of both solutions is 4.00.
(a) (i)Write an expression for the Ka of Cl (CH2)3CO2H(aq).
Ka =
[1]
(ii)Write a mathematical expression to describe the relationship between Ka and pKa.
........................................................................................................................................ [1]
(iii)Calculate [H+] in solutions Y and Z.
[H+] = .............................. mol dm–3 [1]
(iv)Calculate the ratio
[HCl ] dissolved in solution Y
.
[Cl (CH2)3CO2H] dissolved in solution Z
[HCl ] dissolved in solution Y
= .............................. [2]
[Cl (CH2)3CO2H] dissolved in solution Z
(b) A buffer solution of pH 5.00 is produced by adding sodium propanoate to 5.00 g of propanoic acid
in 100 cm3 of distilled water.
alculate the mass of sodium propanoate that must be used to produce this buffer solution.
C
The Ka of propanoic acid is 1.35 × 10–5 mol dm–3.
[Mr: propanoic acid, 74.0; sodium propanoate, 96.0]
© UCLES 2021
mass of sodium propanoate = .............................. g [3]
9701/43/O/N/21
5
(c) S
ome dilute sulfuric acid is mixed with a small sample of the buffer solution described in (b).
The final pH of the mixture is close to 1.
Explain this observation.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
[Total: 10]
© UCLES 2021
9701/43/O/N/21
[Turn over
6
3
(a) Define the term electron affinity.
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)Write an equation for the process corresponding to the second ionisation energy of calcium.
Include state symbols.
............................................................................................................................................... [1]
Some data relating to calcium and oxygen are listed. Select relevant data from this list for your
answers to parts (c), (d) and (e).
process
value / kJ mol–1
first ionisation energy of oxygen
+1310
second ionisation energy of oxygen
+3390
first electron affinity of oxygen
–142
second electron affinity of oxygen
+844
enthalpy change for 12 O2(g) + 2e– → O2–(g)
+951
enthalpy change for Ca(s) → Ca2+(g) + 2e–
+1933
lattice energy of CaO(s)
–3517
(c)Oxygen exists as O2 molecules.
Use the data in this question to calculate a value for the bond energy of the O=O bond.
Show all your working.
© UCLES 2021
bond energy = .............................. kJ mol–1 [3]
9701/43/O/N/21
7
(d) (i)
Suggest why the first electron affinity of oxygen is negative.
..............................................................................................................................................
........................................................................................................................................ [1]
(ii)
Suggest why the second electron affinity of oxygen is positive.
..............................................................................................................................................
........................................................................................................................................ [1]
(e)Calculate the enthalpy of formation of calcium oxide, CaO(s).
enthalpy of formation = .............................. kJ mol–1 [2]
(f) The lattice energy of lithium fluoride, LiF(s), is –1022 kJ mol–1.
Identify the factor that causes the lattice energy of calcium oxide to be more exothermic than
that of lithium fluoride. Explain why this factor causes the difference in lattice energies.
.....................................................................................................................................................
............................................................................................................................................... [2]
[Total: 12]
© UCLES 2021
9701/43/O/N/21
[Turn over
8
4Separate samples of 0.02 mol of calcium carbonate and 0.02 mol of barium carbonate are heated
until completely decomposed to the metal oxide and carbon dioxide.
(a)State which of these two Group 2 carbonates requires the higher temperature before it begins
to decompose. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)After decomposition is complete, the 0.02 mol sample of calcium oxide is taken and added to
2.00 dm3 of water. A solution is formed with no solid present. Dilute sulfuric acid is then added
dropwise until a precipitate is seen.
The same procedure is repeated with the 0.02 mol sample of barium oxide, using the same
concentration solution of dilute sulfuric acid.
Identify the sample to which most sulfuric acid must be added to cause a precipitate to appear.
Explain your answer. You should refer to the solubilities of the precipitates and relevant energy
terms in your answer.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [3]
(c) (i)Calculate the mass, in g, of CO2 produced by the decomposition of 0.020 moles of
calcium carbonate.
mass of CO2 = .............................. g [1]
(ii)Calculate the minimum mass, in g, of propane that would, on complete combustion,
produce the same mass of CO2 calculated in (c)(i).
Give your answer to three significant figures.
mass of propane = .............................. g [2]
[Total: 8]
© UCLES 2021
9701/43/O/N/21
9
5
(a)[MnCl 4]2– is a complex ion.
(i)Deduce the oxidation state of manganese in [MnCl 4]2–.
oxidation state = .............................. [1]
(ii)The [MnCl 4]2– complex does not contain any 180° bond angles.
Draw a three-dimensional diagram to show the shape of the [MnCl 4]2– complex.
State one bond angle on your diagram.
Mn
[2]
(b)A solution of cobalt(II) sulfate contains the complex ion [Co(H2O)6]2+.
A solution containing [Co(H2O)6]2+ is reacted separately with an excess of each of NaOH(aq),
NH3(aq) and NaCl (aq).
Write an equation for each of these reactions. State one observation that can be made
immediately after the reaction, include the colour and state of the cobalt-containing product.
(i)[Co(H2O)6]2+ and an excess of NaOH(aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
(ii)[Co(H2O)6]2+ and an excess of NH3(aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
© UCLES 2021
9701/43/O/N/21
[Turn over
10
(iii)[Co(H2O)6]2+ and an excess of NaCl (aq)
equation ...............................................................................................................................
observation ..........................................................................................................................
[2]
(iv)Name the type of reaction that occurs in (b)(iii).
........................................................................................................................................ [1]
(c)Cobalt forms the complex ion [Co(NH3)2(en)2]2+. The abbreviation en is used for the bidentate
ligand 1,2-diaminoethane, H2NCH2CH2NH2. The complex ion shows both geometrical and
optical isomerism.
(i)
Define the term bidentate ligand.
..............................................................................................................................................
........................................................................................................................................ [2]
(ii)Draw three-dimensional diagrams for the two optical isomers of [Co(NH3)2(en)2]2+.
Each en ligand can be represented using
N
Co
N
.
Co
[2]
© UCLES 2021
[Total: 14]
9701/43/O/N/21
11
6An excess of sodium iodide is added to a solution of copper(II) sulfate. Iodine and a white precipitate
of copper(I) iodide are formed.
(a)Write an equation for the reaction that occurs.
............................................................................................................................................... [1]
(b) (i)Explain why the copper(II) sulfate solution is coloured.
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
........................................................................................................................................ [4]
(ii)Suggest why the precipitate of copper(I) iodide is white.
..............................................................................................................................................
........................................................................................................................................ [1]
(c)Use suitable E o values from the Data Booklet to predict whether iodide ions can reduce Cu2+
to Cu+ under standard conditions. Explain your answer.
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
(d)An excess of sodium iodide is added to copper(II) sulfate solution. Copper(I) iodide forms as
a precipitate. After precipitation, [Cu+] is much lower than 1.0 mol dm–3.
Use this information and your answer to (c) to explain how the relevant electrode potentials
change and hence why I– ions can reduce Cu2+ ions.
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [2]
© UCLES 2021
[Total: 10]
9701/43/O/N/21
[Turn over
12
7The structure of phenylethanoic acid is shown.
OH
O
(a) G
ive the number of different peaks in the carbon-13 (13C) NMR spectrum of phenylethanoic
acid.
number of peaks = .............................. [1]
(b)Phenylethanoic acid, ethanol and phenol can all behave as acids.
Compare and explain the relative acidities of these three compounds.
............................................ > ............................................ > ............................................
most acidic
least acidic
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
.....................................................................................................................................................
............................................................................................................................................... [4]
(c)Phenylethanoic acid can be synthesised using benzene as the starting material.
In the first stage of this synthesis, benzene reacts with chloromethane in the presence of an
Al Cl 3 catalyst to form methylbenzene.
Chloromethane reacts with Al Cl 3 to form two ions. One of these is the carbocation +CH3.
(i)Write an equation for the reaction between chloromethane and Al Cl 3.
........................................................................................................................................ [1]
(ii)Draw the mechanism of the reaction between benzene and +CH3. Include all relevant curly
arrows, charges and the structure of the intermediate.
intermediate
CH3
+
CH3
[3]
© UCLES 2021
9701/43/O/N/21
13
(d)A three-step synthesis of phenylethanoic acid from methylbenzene is shown.
Br
step 1
step 2
compound
Q
OH
step 3
O
(i)State reagents and conditions for step 1.
........................................................................................................................................ [1]
(ii)Suggest the structure of compound Q.
[1]
(iii)State reagents and conditions for steps 2 and 3.
step 2 ...................................................................................................................................
step 3 ...................................................................................................................................
[2]
(iv)Draw the structure of an organic by-product that forms in step 1.
[1]
© UCLES 2021
[Total: 14]
9701/43/O/N/21
[Turn over
14
8Phenylamine, C6H5NH2, and ethylamine, C2H5NH2, can be distinguished by adding aqueous
bromine.
(a)State what is seen when aqueous bromine is added to phenylamine.
.....................................................................................................................................................
............................................................................................................................................... [2]
(b)Suggest what is seen when aqueous bromine is added to ethylamine.
............................................................................................................................................... [1]
(c)Draw the structure of the organic product formed when an excess of aqueous bromine is
added to phenylamine.
[1]
(d)Name the product you have drawn in (c).
............................................................................................................................................... [1]
© UCLES 2021
[Total: 5]
9701/43/O/N/21
15
9Compound T is made by a three-stage synthesis.
(a)In stage 1, phenylethanoic acid reacts with a suitable reagent to form compound R.
R
phenylethanoic acid
OH
stage 1
Cl
O
O
Suggest a suitable reagent for stage 1.
............................................................................................................................................... [1]
(b)In stage 2, compound R reacts with ethylamine to form compound S.
R
S
H
Cl
stage 2
N
+ C2H5NH2 O
O
(i)Name the functional group formed in stage 2.
........................................................................................................................................ [1]
(ii)Identify the other product formed in stage 2.
........................................................................................................................................ [1]
(c)In stage 3, compound S reacts with a suitable reagent to form compound T.
S
T
H
N
stage 3
H
N
O
(i)State the formula of a suitable reagent for stage 3.
........................................................................................................................................ [1]
(ii)Name the type of reaction that occurs in stage 3.
........................................................................................................................................ [1]
© UCLES 2021
9701/43/O/N/21
[Turn over
16
(d)The relative abundance of the molecular ion peak in the mass spectrum of ethylamine is 62.
(i)Calculate the relative abundance of the M+1 peak in the mass spectrum of ethylamine.
relative abundance = .............................. [1]
(ii)The mass spectrum of compound T contains several fragments. The m/e values of two of
these fragments are 29 and 91.
Draw the structures of the ions responsible for these peaks.
structure of ion
m/e
29
91
[2]
(e)The proton (1H) NMR spectrum of compound T shows hydrogen atoms in different environments.
Six of these environments are shown on the structure using letters a, b, c, d, e and f.
H d
b
N
c
f
e
a
Use the letters a, b, c, d, e and f to answer the questions that follow. The questions relate to
the proton (1H) NMR spectrum of T.
Proton d does not cause splitting of the peaks for protons c or e under the conditions used.
Each answer may be one, or more than one, of the letters a, b, c, d, e and f.
(i)Identify the proton or protons with a chemical shift (δ) in the range 6.0 to 9.0.
.............................. [1]
(ii)Identify the proton or protons whose peak will disappear if D2O is added.
© UCLES 2021
.............................. [1]
9701/43/O/N/21
17
(iii)Identify the proton or protons whose peak is a triplet.
.............................. [1]
(iv)Identify the proton or protons with the lowest chemical shift (δ).
.............................. [1]
[Total: 12]
© UCLES 2021
9701/43/O/N/21
[Turn over
18
10 V
aline (Val) and lysine (Lys) are amino acids. The structures of these amino acids can be found in
the Data Booklet.
The isoelectric point of an amino acid is the pH at which it exists as a zwitterion. The isoelectric
point of valine is 6.0. The isoelectric point of lysine is 9.7.
(a)Draw the structure of valine at pH 6.0.
[1]
(b)A solution of lysine is produced with pH 9.7. Dilute sulfuric acid is added slowly until the pH of
the solution is 1.0. The sulfuric acid reacts with lysine to produce different organic ions that are
not present in significant concentrations at pH 9.7.
Draw the structures of three of the organic ions that form during the addition of sulfuric acid in
the boxes. Draw the organic ion present at pH 1.0 in box C.
A
B
C (pH 1.0)
[3]
(c) Draw the structure of the dipeptide Val-Lys. The peptide bond should be shown fully displayed.
[2]
© UCLES 2021
[Total: 6]
9701/43/O/N/21