Name: ________________
Class: _____
CfE Higher Chemistry
Unit One - Chemical Changes & Structure
Homework Booklet
Topic
Mark
1) Controlling The Rate Teacher
Comments:
2) Periodicity
Teacher Comments:
3) Structure & Bonding Teacher
Comments:
Page
2
/19
9
/13
12
/16
For multiple choice questions circle your answer.
Reference may be made to the Chemistry Higher and Advanced Higher Data Booklet.
1) Controlling the Rate
1. The following potential diagram is for a reaction carried out with and without a
catalyst.
The activation energy for the catalysed reaction is
A
B
C
D
30 kJ mol–1
80 kJ mol–1
100 kJ mol–1
130 kJ mol–1.
[Q9. 2011]
2. In a reaction involving gases, an increase in temperature results in
A an increase in activation energy
B an increase in the enthalpy change
C a decrease in the activation energy
D more molecules per second forming an activated complex. [Q26. R2012]
3. In which of the following will both changes result in an increase in the rate of a chemical
reaction?
A A decrease in activation energy and an increase in the frequency of collisions.
B An increase in activation energy and a decrease in particle size.
C An increase in temperature and an increase in the particle size.
D An increase in concentration and a decrease in the surface area of the reactant
particles.
[Q25. R2013]
2
4. Which of the following diagrams represents an exothermic reaction which is most likely to
take place at room temperature?
[Q26. R2013]
5.
In area X
A
molecules always form an activated complex
B
no molecules have the energy to form an activated complex
C
collisions between molecules are always successful in forming products
D
all molecules have the energy to form an activated complex.
[Q7. 2008]
3
6.
Graph X was obtained when 1 g of calcium carbonate powder reacted with excess
dilute hydrochloric acid at 20 °C.
Which curve would best represent the reaction of 0·5 g lump calcium carbonate with
excess of the same dilute hydrochloric acid?
[Q22.R2014]
7.
A
Which of the following is not a correct statement about the effect of a catalyst? The
catalyst
provides energy so that more molecules have successful collisions
B
lowers the energy which molecules need for successful collisions
C
provides an alternative route to the products
D
forms bonds with reacting molecules.
8.
For any chemical, its temperature is a measure of
A
the average kinetic energy of the particles that react
B
the average kinetic energy of all the particles
C
the activation energy
D
the minimum kinetic energy required before reaction occurs.
[Q26.RSQP]
4
[Q4.2010]
9.
Which line in the table is correct for curves Q and R in the above graph?
[Q23.R2014]
10.
When a catalyst is used, the activation energy of the forward reaction is reduced to 35
kJ mol−1. What is the activation energy of the catalysed reverse reaction?
A
30 kJ mol−1
B
35 kJ mol−1
C
65 kJ mol−1
D
190 kJ mol−1
[Q24.R2014]
5
11.
When copper carbonate is reacted with excess acid, carbon dioxide is produced.
The curves shown above were obtained under different conditions. The change from
P to Q could be brought about by
A
increasing the concentration of the acid
B
decreasing the mass of copper carbonate
C
decreasing the particle size of the copper carbonate
D
adding a catalyst
12.
The potential energy diagram for the reaction below is shown.
[Q24.RSQP]
ΔH, in kJ mol–1, for the forward reaction is
A
+361
B
–93
C
–227
D
–361.
[Q25.RSQP]
6
13.
(a)
A student investigated the effect of changing temperature on the rate of chemical
reaction. The results from the investigation are shown in the graph below.
(i)
Use the graph to determine the temperature rise required to double the rate of
reaction.
1
(ii) The reaction time recorded in one experiment was 25 s.
Use the graph to determine the temperature, in °C, of this reaction.
1
(iii) The answer below was taken from a student’s examination paper. The answer is
incorrect. Give the correct explanation.
Question: Why does a small increase in temperature produce a large increase in
reaction rate?
Student answer: Because rising temperature increases the activation energy which
increases the number of collisions which speeds up the reaction greatly.
Correct Answer:
1
(b) Collision theory can be used to explain reaction rates.
Collision theory states that for two molecules to react, they must first collide with one
another.
State two conditions necessary for the collisions to result in the formation of
products.
[Q11a. 2009] [Q9.R2014]
7
2
(5)
14.
The graph shows the distribution of kinetic energy for molecules in a reaction mixture
without a catalyst.
(a)
On the diagram, label the activation energy (EA) for the catalysed reaction.
1
(b)
Explain why using a catalyst allows industrial processes to be carried out at lower
temperatures.
1
8
2) Periodicity
1.
2.
Which of the following elements has the greatest attraction for bonding electrons?
A
Lithium
B
Chlorine
C
Sodium
D
Bromine
[Q1. R2013]
The spike graph shows the variation in successive ionisation energies of an element, Z.
In which group of the Periodic Table is element Z?
3.
A
1
B
3
C
4
D
6
[Q1.R2014]
Atoms of nitrogen and element X form a bond in which the electrons are shared
equally.
Element X could be
A
carbon
B
oxygen
C
chlorine
D
phosphorus.
[Q4. RSQP]
9
4.
Which of the following elements would require the most energy to convert one mole of
gaseous atoms into gaseous ions each carrying two positive charges?
(You may wish to use the data booklet.)
A
B
C
D
5.
Scandium
Titanium
Vanadium
Chromium
[Q2.RSQP]
The Periodic Table allows chemists to make predictions about the properties of
elements.
(a) The elements lithium to neon make up the second period of the Periodic Table.
Explain why the atoms decrease in size from lithium to neon?
1
(b) On descending Group 1 from lithium to caesium, the electronegativity of the elements
decreases.
Explain clearly why the electronegativity of elements decreases as you go down
the group.
[Q1.R2012]
6.
The first ionisation energy of an element is defined as the energy required to remove
one mole of electrons from one mole of atoms in the gaseous state. The graph shows
the first ionisation energies of the Group 1 elements.
10
2
Clearly explain why the first ionisation energy decreases down this group.
[Q11ai.2010]
7.
2
The answer below was taken from a student’s examination paper.
The answer is incorrect. Give the correct explanation.
Question: Explain the difference in atomic size between potassium and chlorine
atoms.
Student answer: A potassium nucleus has 19 protons but a chlorine nucleus has only 17
protons. The greater pull on the outer electron in the potassium atom means the atomic
size of potassium is less than that of chlorine.
Correct Answer:
1
[Q11b. 2009]
8. (a) On crossing the third period from left to right there is a general increase in the first
ionisation energy of the elements.
(i) Why does the first ionisation energy increase across the period?
1
(ii) Write an equation corresponding to the first ionisation energy of chlorine. 1
(a)
The electronegativities of elements in the third period are listed on in the data book.
Why is no value provided for the noble gas, argon?
[Q2.2011]
11
1
(3)
12
6) Oxidising and Reducing Agents & Chemical Analysis
1.
In which reaction is hydrogen gas acting as an oxidising agent?
[Q39.2010]
2.
During a redox process in acid solution, iodate ions are converted into iodine.
To balance the equation, what is the value of x?
A
B
C
D
3.
2
6
10
12
The following reactions take place when nitric acid is added to zinc.
How many moles of
A
B
C
D
4.
[Q37.2011]
𝑁𝑂3− (aq) are reduced by one mole of zinc?
2/3
1
3/2
2
[Q38.2011]
Four metals W, X, Y and Z and their compounds behaved as described.
(i) Only X, Y and Z reacted with dilute hydrochloric acid.
(ii) The oxides of W, X and Y were reduced to the metal when heated
with carbon powder. The oxide of Z did not react.
(iii) A displacement reaction occurred when X was added to an aqueous
solution of the nitrate of Y.
What is the correct order of reactivity of these metals (most reactive first)?
A
B
C
D
W, Y, X, Z
W, X, Y, Z
Z, X, Y, W
Z, Y, X, W
[Q37.2011]
13
5.
A student obtained a certain volume of carbon dioxide by the reaction of 20 cm 3 of 2
mol l-1 hydrochloric acid with excess sodium carbonate.
Which solution of sulfuric acid would give the same final volume of carbon
dioxide when added to excess sodium carbonate?
A
B
C
D
6.
10 cm3 of
20 cm3 of
10 cm3 of
20 cm3 of
2 mol
2 mol
4 mol
4 mol
l-1 sulfuric acid
l-1 sulfuric acid
l-1 sulfuric acid
l-1 sulfuric acid
[Q22.R2011]
Sulphur dioxide gas is denser than air and is very soluble in water.
Which of the following diagrams shows the most appropriate apparatus for collecting
and measuring the volume of sulphur dioxide given off in a reaction?
A
B
C
D
[Q30. R2011]
14
7.
The correct method of filling a 20 cm3 pipette is to draw the liquid into the pipette
A doing it slowly at the end, until the top of the meniscus touches the mark
B doing it slowly at the end, until the bottom of the meniscus touches the mark
C to above the mark and then release liquid from the pipette until the top of the
meniscus touches the mark
D to above the mark and then release liquid from the pipette until the bottom of
the meniscus touches the mark.
[Q29.R2014]
8.
A 0·10 mol l−1 solution could be prepared most accurately from a 1·0 mol l−1 solution
using
A
B
C
D
9.
1 cm3 dropping pipette and a 10 cm3 measuring cylinder
10 cm3 measuring cylinder and a 100 cm3 volumetric flask
25 cm3 pipette and a 250 cm3 volumetric flask
50 cm3 burette and a 500 cm3 measuring cylinder..
[Q30.R2014]
45 cm3 of a solution could be most accurately measured out using a
A
B
C
D
10.
a
a
a
a
50 cm3 beaker
50 cm3 burette
50 cm3 pipette
50 cm3 measuring cylinder.
[Q29.R2013]
The alcohol content of wine was analysed by four students. Each student carried out
the experiment three times.
The most reproducible results were obtained by
A Student A
B Student B
C Student C
D Student D.
[Q30.R2012]
15
11.
Aluminium carbonate can be produced by the following reaction.
The most suitable method for obtaining a sample of the aluminium carbonate is
A
B
C
D
12.
collection over water
distillation
evaporation
filtration.
[Q22.R2011]
An organic chemist is attempting to synthesise a fragrance compound by the following
chemical reaction.
After one hour, a sample is removed and compared with pure samples of compounds X
and Y using thin-layer chromatography.
Which of the following chromatograms shows that the reaction has produced a pure
sample of the fragrance compound?
A
B
C
D
[Q29. R2012]
16
13.
Dark blue compounds can be made by reacting ammonia with copper ions.
To determine the number of ammonia molecules that react with each copper
ion, a student prepared the following mixtures and measured their colour
intensity.
(a)
Complete the table to show the volume of NH3 solution required for the
final experiment.
1
(b)
The number of ammonia molecules that react with each copper ion can be
found from the mixture with the greatest colour intensity.
How many ammonia molecules react with each copper ion?
1
[Q9.R2013]
14.
The chlorine used in the experiment is made in a redox reaction between
permanganate ions and chloride ions.
The ion-electron equations for the oxidation and reduction reactions are
Write a balanced equation for the reaction of permanganate ions with
chloride ions to produce chlorine gas.
1
[Q2c.R2011]
17
15.
Solutions containing iodine are used to treat foot rot in sheep.
The concentration of iodine in a solution can be determined by titrating with
a solution of thiosulfate ions.
(a)
Write an ion-electron equation for the reaction of the oxidising agent in the
titration.
1
(b)
Three 20·0 cm3 samples of a sheep treatment solution were titrated with
0·10 mol l–1 thiosulfate solution.
The results are shown below.
(i)
Why is the volume of sodium thiosulfate used in the calculation taken to be 18·15 cm 3,
although this is not the average of the three titres in the table?
1
(ii)
Calculate the concentration of iodine, in mol
Show your working clearly.
18
l–1,
in the foot rot treatment solution.
3
(iii) Describe how to prepare 250
thiosulfate, Na2S2O3.
cm3
of a 0·10 mol
l−1
standard solution of sodium
Your answer should include the mass, in g, of sodium thiosulfate required.
3
[Q10.R2013]
16.
When forensic scientists analyse illegal drugs, anaesthetics such as lidocaine are
sometimes found to be present.
The gas chromatogram below is from an illegal drug.
19
(a)
The structures of benzocaine and tetracaine are shown below.
Suggest why benzocaine has a shorter retention time than tetracaine.
1
(b)
Why is it difficult to obtain accurate values for the amount of lidocaine present in a
sample containing large amounts of caffeine?
1
(c)
Add a peak to the diagram below to complete the chromatogram for a second
sample that only contains half the amount of tetracaine compared to the first.
1
[Q6d.R2013]
20
17.
When ClO–(aq) acts as a bleach, it is reduced to produce the Cl–(aq) ion.
Complete the above to form the ion-electron equation for the reduction reaction.
1
[Q7c.R2011
]
18.
A
A student carried out an investigation to measure the nitrite level in the school water
supply.
compound, which reacts with the nitrite ions to
form a product that absorbs light, is added to water
samples. The higher the concentration of nitrite
ions present in a water sample, the greater the
amount of light absorbed.
(a)
The student prepared potassium nitrite solutions of known concentration
by diluting samples from a stock solution.
(i)
(ii)
Calculate the mass, in mg, of potassium nitrite, KNO2, needed to make
1 litre of stock solution with a nitrite ion concentration of 250 mg l –1.
2
Describe how the weighed potassium nitrate is dissolved to prepare the stock solution
to ensure that its concentration is accurately known.
2
(iii) Why should the student use distilled or deionised water rather than tap water when
dissolving the potassium nitrite?
21
1
(iv)
To prepare a solution with a nitrite ion concentration of 0·05 g l–1 the student dilutes
the stock solution. Why is this method more accurate than preparing a solution by
weighing out potassium nitrite?
1
(b)
The graph below shows results for five solutions of potassium nitrite and
a sample of distilled water.
The results for four tap water samples are shown below.
What is the concentration of nitrite ions, in mg l–1, in the tap water?
22
1
(7)
[Q9.R2011]
23
3) Structure & Bonding
1.
The diagram shows the melting points of successive elements across a period in the
Periodic Table.
Which of the following is a correct reason for the low melting point of element Y?
A
B
C
D
2.
has weak ionic bonds.
has weak covalent bonds.
has weakly-held outer electrons.
has weak forces between molecules.
[Q5. R2013]
Which of the following does not contain covalent bonds?
A
B
C
D
3.
It
It
It
It
Hydrogen gas
Helium gas
Nitrogen gas
Solid sulphur
[Q2. R2012]
Diamond has
A
B
C
D
an ionic lattice structure
a covalent network structure
covalent molecules linked by London dispersion forces
covalent sheets with only London dispersion forces acting between sheets.
[Q1. RSQP]
24
4.
Which type of bonding is never found in elements?
A
B
C
D
5.
Covalent bonding
Hydrogen bonding
London dispersion forces
Permanent dipole-permanent dipole interactions
[Q5. RSQP]
Atoms of nitrogen and element X form a bond in which the electrons are shared equally.
Element X could be
A
B
C
D
7.
[Q4. R2013]
Which of the following is not an example of a Van der Waals’ force?
A
B
C
D
6.
Metallic
London dispersion forces
Polar covalent
Non-polar covalent
carbon
oxygen
chlorine
phosphorus.
[Q4. R2012]
The structures for molecules of four liquids are shown below.
Which liquid will be the most viscous?
A
B
C
D
[Q6. R2013]
25
8.
The shapes of some common molecules are shown below and each contains at least one
polar bond.
Which molecule is non-polar?
A
B
C
D
[Q5. R2014]
9.
10.
11.
Which of the following chlorides is likely to have the most ionic character?
A
LiCl
B
CsCl
C
BeCl2
D
CaCl2
[Q4. RSQP]
Which line in the table represents the solid in which only London dispersion forces are
overcome when the substance melts?
[Q6. R2012]
Which of the following chlorides is likely to have the most ionic character?
A
LiCl
B
CsCl
C
BeCl2
D
CaCl2
[Q4. RSQP]
26
12.
Information about four elements from the third period of the Periodic Table is shown in
the table.
(a)
Complete the table to show the bonding and structure for each element.
(b)
Why is there a decrease in the size of atoms across the period from aluminium to sulfur?
[Q1a,b.R2014]
13.
2
1
Hydrogen gas has a boiling point of –253 °C.
Explain clearly why hydrogen is a gas at room temperature.
In your answer you should name the intermolecular forces involved and indicate how
they arise.
[9a.2008]
27
2
14.
Electronegativity values can be used to predict the type of bonding present in
substances.
The type of bonding between two elements can be predicted using the diagram below.
(a) Using the information in the diagram, state the highest average electronegativity found in
ionic compounds.
1
(b) The diagram can be used to predict the bonding in tin iodide.
Electronegativity of tin = 1·8
Electronegativity of iodine = 2·6
Average electronegativity = 2·2
Difference in electronegativity = 0·8
Predict the type of bonding in tin iodide.
28
1
(c) The electronegativities of arsenic and chlorine are shown below.
Electronegativity of arsenic = 2·2
Electronegativity of chlorine = 3·0
Place a small cross on the diagram to show the position of arsenic chloride.
Show calculations clearly.
2
[Q7,R2012]
15.
(4)
The structures below show molecules that contain chlorine atoms.
The compounds shown above are not very soluble in water.
Trichloromethane is around ten times more soluble in water than tetrachloromethane.
Explain clearly why trichloromethane is more soluble in water than
tetrachloromethane.
Your answer should include the names of the intermolecular forces involved.
3
[Q3a,R2013]
29