1
Dilute hydrochloric acid reacts with sodium carbonate solution.
2HCl (aq) + Na2CO3(aq) → 2NaCl (aq) + H2O(l) + CO2(g)
(a) Explain why effervescence is seen during the reaction.
....................................................................................................................................................
.............................................................................................................................................. [1]
(b) Dilute hydrochloric acid was titrated with sodium carbonate solution.
•
•
•
•
(i)
10.0 cm3 of 0.100 mol / dm3 hydrochloric acid were placed in a conical flask.
A few drops of methyl orange indicator were added to the dilute hydrochloric acid.
The mixture was titrated with sodium carbonate solution.
16.2 cm3 of sodium carbonate solution were required to react completely with the acid.
What colour would the methyl orange indicator be in the hydrochloric acid?
....................................................................................................................................... [1]
(ii)
Calculate how many moles of hydrochloric acid were used.
............................ mol [1]
(iii)
Use your answer to (b)(ii) and the equation for the reaction to calculate the number of
moles of sodium carbonate that reacted.
............................ mol [1]
(iv)
Use your answer to (b)(iii) to calculate the concentration of the sodium carbonate solution
in mol / dm3.
............................ mol / dm3 [2]
(c) In another experiment, 0.020 mol of sodium carbonate were reacted with excess hydrochloric
acid.
Calculate the maximum volume (at r.t.p.) of carbon dioxide gas that could be made in this
reaction.
............................ dm3 [3]
[Total: 9]
2
(a) Alkanes and alkenes are examples of hydrocarbons.
(i)
What is meant by the term hydrocarbon?
.............................................................................................................................................
....................................................................................................................................... [1]
(ii)
Give the general formula of straight-chain
alkanes, ..............................................................................................................................
alkenes. ..............................................................................................................................
[2]
(b) A compound X contains carbon, hydrogen and oxygen only.
X contains 54.54% of carbon by mass, 9.09% of hydrogen by mass and 36.37% of oxygen by
mass.
(i)
Calculate the empirical formula of compound X.
[2]
(ii)
Compound X has a relative molecular mass of 88.
Deduce the molecular formula of compound X.
[2]
(c) An ester has the molecular formula C3H6O2.
Name and give the structural formulae of two esters with the molecular formula C3H6O2.
name of ester
structural formula
[4]
(d) Name the ester produced from the reaction of propanoic acid and methanol.
.............................................................................................................................................. [1]
(e) A polyester is represented by the structure shown.
(i)
O
O
C
C
O
O
What type of polymerisation is used for the production of polyesters?
....................................................................................................................................... [1]
(ii)
Which simple molecule is removed when the polyester is formed?
....................................................................................................................................... [1]
(iii)
Complete the diagrams below to show the structures of the monomers used to produce
the polyester. Show all atoms and bonds.
C
C
O
O
[2]
[Total: 16]
3
(a) A compound, X, contains 55.85% carbon, 6.97% hydrogen and 37.18% oxygen.
(i)
How does this prove that compound X contains only carbon, hydrogen and oxygen?
....................................................................................................................................... [1]
(ii)
Use the above percentages to calculate the empirical formula of compound X.
....................................................................................................................................... [2]
(iii)
The Mr of X is 86.
What is its molecular formula?
....................................................................................................................................... [2]
(b) (i)
Bromine water changes from brown to colourless when added to X.
What does this tell you about the structure of X?
....................................................................................................................................... [1]
(ii)
Magnesium powder reacts with an aqueous solution of X. Hydrogen is evolved.
What does this tell you about the structure of X?
....................................................................................................................................... [1]
(iii)
X contains two different functional groups.
Draw a structural formula of X.
[1]
[Total: 8]
4
Two salts can be made from potassium hydroxide and sulfuric acid. They are potassium sulfate,
K2SO4, and the acid salt potassium hydrogen sulfate, KHSO4. They are both made by titration.
burette filled with
sulfuric acid
conical flask
25.0 cm3 of potassium hydroxide solution
(a) 25.0 cm3 of potassium hydroxide, concentration 2.53 mol / dm3, was neutralised by 28.2 cm3 of
dilute sulfuric acid.
2KOH(aq) + H2SO4(aq) o K2SO4(aq) + 2H2O(l) Calculate
the concentration of the sulfuric acid.
number of moles of KOH used = ............................
number of moles of H2SO4 needed to neutralise the KOH = ............................
concentration of dilute sulfuric acid = ............................ mol / dm3
[3]
(b) ! 4 ! 7!! !
indicator used in the titration.
(i)
Describe how you could obtain a solution of potassium sulfate without the indicator.
.............................................................................................................................................
....................................................................................................................................... [2]
(ii)
Potassium hydrogen sulfate can be made by the following reaction.
KOH(aq) + H2SO4(aq) o KHSO4(aq) + H2O(l)
Suggest how you could make a solution of potassium hydrogen sulfate without using an indicator.
.............................................................................................................................................
.............................................................................................................................................
....................................................................................................................................... [2]
(c) Describe a test which would distinguish between aqueous solutions of potassium
sulfate and sulfuric acid
test .................................................................................................................................
result ..............................................................................................................................
[2]
[Total: 9]
5
The Atacama desert in Chile has deposits of the salt sodium nitrate. Very large amounts of this
salt were exported to Europe for use as a fertiliser. After the introduction of the Haber process in
1913, this trade rapidly diminished.
(a)
a)
Explain why the introduction of the Haber process reduced the demand for
sodium nitrate.
.............................................................................................................................................
....................................................................................................................................... [2]
(ii)
Suggest why surface deposits of sodium nitrate only occur in areas with very low rainfall
such as desert areas.
....................................................................................................................................... [1]
(iii)
The desert has smaller surface deposits of potassium nitrate.
Suggest why potassium nitrate is a better fertiliser than the sodium salt.
....................................................................................................................................... [1]
(b) All nitrates decompose when heated. The extent to which a nitrate decomposes is
determined by the metal in the salt.
(i)
Sodium nitrate decomposes to form sodium nitrite, NaNO2.
Write the equation for decomposition of sodium nitrate.
....................................................................................................................................... [2]
(ii)
Sodium nitrite is a reducing agent.
What would be observed if an excess of sodium nitrite solution was added to a solution
of acidified potassium manganate(VII)?
....................................................................................................................................... [2]
(iii)
Copper(II) nitrate decomposes to form copper(II) oxide, nitrogen dioxide and oxygen.
What is the relationship between the extent of decomposition and the reactivity of the
metal in the nitrate?
.............................................................................................................................................
....................................................................................................................................... [1]
(c) The equation for the decomposition of copper(II) nitrate is given below.
2Cu(NO3)2 → 2CuO + 4NO2 + O2
(i)
Predict what you would observe when copper(II) nitrate is heated.
.............................................................................................................................................
.............................................................................................................................................
....................................................................................................................................... [3]
(ii)
Copper(II) nitrate forms a series of hydrates with the formula Cu(NO3)2.xH2O.
All these hydrates decompose to form copper(II) oxide.
1 mole of Cu(NO3)2.xH2O forms 1 mole of CuO.
What is meant by 1 mole of a substance?
.............................................................................................................................................
....................................................................................................................................... [2]
(iii)
7.26 g of a hydrate, Cu(NO3)2.xH2O, formed 2.4 g copper(II) oxide.
number of moles of CuO formed = ......................
number of moles of Cu(NO3)2.xH2O in 7.26 g = ......................
mass of 1 mole of Cu(NO3)2.xH2O = ...................... g
mass of 1 mole of Cu(NO3)2 is 188 g
the value of x in this hydrate = ......................
[4]
[Total: 18]
6
Use your copy of the Periodic Table to help you answer these questions.
(a) Predict the formula of each of the following compounds.
(i)
(ii)
(iii)
aluminium
fl
uoride ........................................................................................................ [1]
arsenic
oxide ................................................................................................................
[1]
silicon
bromide ..............................................................................................................
[1]
(b) Deduce the formula of each of the following ions.
(i)
phosphide .............................................................................................................
........ [1]
(ii)
barium ...................................................................................................................
........ [1]
(iii)
francium ................................................................................................................
........ [1]
(c) Draw a diagram showing the arrangement of the valency electrons in one
molecule of the covalent compound carbon dioxide.
Use x to represent an electron from a carbon atom. Use o to
represent an electron from an oxygen atom.
[3]
[Total: 9]
1
The law of constant composition states that all pure samples of a compound contain the same
elements in the same proportion by weight.
A typical experiment to test this law is to prepare the same compound by different methods
and then show that the samples have the same composition.
Methods of making copper(II) oxide include:
•
•
•
•
heating copper carbonate,
heating copper hydroxide,
heating copper nitrate,
heating copper foil in air.
(a) Complete the following equations.
(i)
(ii)
(iii)
CuCO
3 → ............. + .............
Cu(OH)
2 → ............. + .............
2Cu(NO
3)2 → ............. + 4NO2 + .............
[1]
[1]
[2]
(b) Copper oxide can be reduced to copper by heating in hydrogen.
(i) What colour change would you observe during the reduction?
.......................................................................................................................................
[1]
(ii)
Explain why the copper must be allowed to cool in hydrogen before it is exposed to air.
.......................................................................................................................................
[2]
(iii)
Name another gas which can reduce copper(II) oxide to copper.
.......................................................................................................................................
(iv)
Name a solid which can reduce copper(II) oxide to copper.
[1]
.......................................................................................................................................
[1]
(c) The table below shows the results obtained by reducing the copper(II) oxide
(ci) produced by different methods to copper.
(i)
Complete the table.
mass of
copper(II) oxide / g
mass of
copper / g
CuCO3
2.37
1.89
Cu(OH)2
2.51
1.99
Cu(NO3)2
2.11
1.68
Cu and O2
2.29
1.94
source of copper(II)
oxide
percentage
copper / %
79.7
[2]
(ii)
One of the samples of copper(II) oxide is impure.
Identify this sample and suggest an explanation why the percentage of copper in this sample is
bigger than in the other three samples.
.............................................................................................................................................
....................................................................................................................................... [2]
[Total: 13]
2
(a) A compound X contains 82.76% of carbon by mass and 17.24% of hydrogen by mass.
(i)
Calculate the empirical formula of compound X.
[2]
(ii)
Compound X has a relative molecular mass of 58.
Deduce the molecular formula of compound X.
[2]
(b) Alkenes are unsaturated hydrocarbons.
(i)
State the general formula of alkenes.
....................................................................................................................................... [1]
(ii)
State the empirical formula of alkenes.
....................................................................................................................................... [1]
(c) What is meant by the term unsaturated hydrocarbon?
unsaturated ................................................................................................................................
....................................................................................................................................................
hydrocarbon ...............................................................................................................................
....................................................................................................................................................
[2]
(d) Describe a test that would distinguish between saturated and unsaturated hydrocarbons.
reagent ......................................................................................................................................
observation (saturated hydrocarbon) .........................................................................................
observation (unsaturated hydrocarbon) .....................................................................................
[3]
(e) Addition polymers can be made from alkenes. The diagram shows part of an addition polymer.
C 2H 5 H
C 2H 5 H
C
C
C
C
H
H
H
H
(i)
Draw a circle on the diagram to show one repeat unit in this polymer.
(ii)
Give the structure and the name of the monomer used to make this polymer.
[1]
structure
name ............................................................................................................................. [2]
(iii)
Give the structure of an isomer of the alkene in (e)(ii).
[1]
[Total: 15]
3
Ethanol is manufactured from glucose, C 6H12O6, by fermentation according to the following
equation. C6H12O6 → 2C2H5OH + 2CO2
(a) State the conditions required for this reaction.
....................................................................................................................................................
.............................................................................................................................................. [2]
(b) In an experiment, 30.0 g of glucose was fermented.
(i)
Calculate the number of moles of glucose in 30.0 g.
......................... mol [2]
(ii)
Calculate the maximum mass of ethanol that could be obtained from 30.0 g of glucose.
......................... g [2]
(iii)
Calculate the volume of carbon dioxide at room temperature and pressure that can be
obtained from 30.0 g of glucose.
......................... dm3 [1]
(c) Ethanol can also be manufactured from ethene.
(i)
Name the raw material which is the source of ethene.
....................................................................................................................................... [1]
(ii)
Write a balanced equation for the manufacture of ethanol from ethene.
....................................................................................................................................... [1]
[Total: 9]
4 (a)
Definethefollowing
(i) the mole
....................................................................................................................................
.............................................................................................................................. [1]
(ii) the Avogadro constant
....................................................................................................................................
.............................................................................................................................. [1]
(b) Which two of the following contain the same number of molecules?
Show how you arrived at your answer.
2.0 g of methane, CH4
8.0 g of oxygen, O2
2.0 g of ozone, O3
8.0 g of sulfur dioxide, SO2
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(c) 4.8 g of calcium is added to 3.6 g of water. The following reaction occurs.
Ca + 2H2O → Ca(OH)2 + H2
(i) the number of moles of Ca = ....................
the number of moles of H2O = ....................
[1]
(ii) Which reagent is in excess? Explain your choice.
....................................................................................................................................
.............................................................................................................................. [2]
(iii) Calculate the mass of the reagent named in (ii) which remained at the end of the
experiment.
....................................................................................................................................
.............................................................................................................................. [1]
[Total: 8]
5
Quantities of chemicals, expressed in moles, can be used to find the formula of a
compound, to establish an equation and to determine reacting masses.
(a) A compound contains 72% magnesium and 28% nitrogen. What is its empirical
formula?
[2]
(b) A compound contains only aluminium and carbon. 0.03 moles of this compound reacted
with excess water to form 0.12 moles of Al(OH)3 and 0.09 moles of CH4.
Write a balanced equation for this reaction.
[2]
(c) 0.07 moles of silicon reacts with 25 g of bromine.
Si
+
2Br2
SiBr4
(i) Which one is the limiting reagent? Explain your choice.
[3]
(ii) How many moles of SiBr4 are formed?
[1]
[Total: 8]
6
(a
The following method is used to make crystals of hydrated nickel sulphate.
An excess of nickel carbonate, 12.0 g, was added to 40 cm3 of sulphuric acid, 2.0
mol/dm3. The unreacted nickel carbonate was filtered off and the filtrate evaporated to
obtain the crystals.
NiSO4 + CO2 + H2O
NiCO3 + H2SO4
NiSO4 + 7H2O
NiSO4.7H2O
Mass of one mole of NiSO4.7H2O = 281 g
Mass of one mole of NiCO3 = 119 g
(i) Calculate the mass of unreacted nickel carbonate.
Number of moles of H2SO4 in 40 cm3 of 2.0 mol/dm3 acid = 0.08
Number of moles of NiCO3 reacted =
Mass of nickel carbonate reacted =
g
Mass of unreacted nickel carbonate =
g
[3]
(ii) The experiment produced 10.4 g of hydrated nickel sulphate. Calculate the
percentage yield.
The maximum number of moles of NiSO4 .7H2O that could be formed =
The maximum mass of NiSO4 .7H2O that could be formed =
g
The percentage yield =
%
[3]
(b) In the above method, a soluble salt was prepared by neutralising an acid with an
insoluble base. Other salts have to be made by different methods.
(i) Give a brief description of how the soluble salt, rubidium sulphate could be made
from the soluble base, rubidium hydroxide.
[3]
(ii) Suggest a method of making the insoluble salt, calcium fluoride.
[3]
1
Chemists use the concept of the mole to calculate the amounts of chemicals involved in a
reaction.
(a) Define mole.
[1]
(b) 3.0 g of magnesium was added to 12.0 g of ethanoic acid.
Mg + 2CH3COOH → (CH3COO)2Mg + H2
The mass of one mole of Mg is 24 g.
The mass of one mole of CH3COOH is 60 g.
(i) Which one, magnesium or ethanoic acid, is in excess? You must show your
reasoning.
[3]
(ii) How many moles of hydrogen were formed?
[1]
(iii) Calculate the volume of hydrogen formed, measured at r.t.p.
[2]
(c) In an experiment, 25.0 cm3 of aqueous sodium hydroxide, 0.4 mol / dm3, was neutralised
by 20.0 cm3 of aqueous oxalic acid, H2C2O4.
2NaOH + H2C2O4 → Na2C2O4 +2H2O
Calculate the concentration of the oxalic acid in mol / dm3.
(i) Calculate the number of moles of NaOH in 25.0 cm3 of 0.4 mol / dm3 solution.
[1]
(ii) Use your answer to (i) and the mole ratio in the equation to find out the number of
moles of H2C2O4 in 20 cm3 of solution.
[1]
(iii) Calculate the concentration, mol / dm3, of the aqueous oxalic acid.
[2]
2
Soluble salts can be made using a base and an acid.
(a) Complete this method of preparing dry crystals of the soluble salt
cobalt(II) chloride-6-water from the insoluble base cobalt(II) carbonate.
step 1
Add an excess of cobalt(II) carbonate to hot dilute hydrochloric acid.
step 2
step 3
step 4
[4]
(b) (i) 5.95 g of cobalt(II) carbonate were added to 40 cm3 of hydrochloric acid, concentration
2.0 mol / dm3.
Calculate the maximum yield of cobalt(II) chloride-6-water and show that the cobalt(II)
carbonate was in excess.
CoCO3 + 2HCl → CoCl2 + CO2 + H2O
CoCl2 + 6H2O → CoCl2.6H2O
maximum yield:
number of moles of HCl used = ………………………………………………...…..…….
number of moles of CoCl2 formed = ……………………………………………..….……
number of moles of CoCl2.6H2O formed = ………………………………………..…..…
mass of one mole of CoCl2.6H2O = 238 g
maximum yield of CoCl2.6H2O = …………………………………………………..…..… g
to show that cobalt(II) carbonate is in excess:
number of moles of HCl used = ……………………….……… (use your value from above)
mass of one mole of CoCO3 = 119 g
number of moles of CoCO3 in 5.95 g of cobalt(II) carbonate = ………………………… [5]
(ii) Explain how these calculations show that cobalt(II) carbonate is in excess.
[1]
[Total: 10]
3
(a) Propane reacts with chlorine to form a mixture of chloropropanes. This is
a photochemical reaction.
(i)
What is meant by the phrase photochemical reaction?
...............................................................................................................................
............................................................................................................................. [1]
(ii) The products of this reaction include two isomers, one of which has the following
structural formula.
H
H
H
H
C
C
C
H
H
H
Cl
Draw the structural formula of the other isomer.
[1]
(iii)
Explain why these two different compounds are isomers.
....................................................................................................................................
............................................................................................................................. [2]
(b) Bond breaking is an endothermic change and bond forming is an exothermic
change.
Bond energy is the amount of energy in kJ / mol needed to break one mole
of the specified bond.
H
H
H
H
C
C
C
H
H
H
H
+
C l
Cl
→
H
H
H
H
C
C
C
H
H
Cl
+
H
Use the following bond energies to determine whether this reaction
is exothermic or endothermic. You must show your reasoning.
bond
bond energies in
kJ / mol
C–Cl
338
C–H
412
Cl –Cl
242
H–Cl
431
C–C
348
....................................................................................................................................................
....................................................................................................................................................
....................................................................................................................................................
.............................................................................................................................................. [3]
H
(c)
Chloropropane can be hydrolysed to propanol, CH3CH2CH2OH, by sodium
hydroxide.
Write the equation for this reaction.
........................................................................................................................ [2]
(ii)
Propanol can be dehydrated. It loses a water molecule to form a hydrocarbon.
Give the name and structural formula of this hydrocarbon.
name .................................................
structural formula
[2]
(iii)
Propanol is oxidised to a carboxylic acid by acidifiedpotassiummanganate(
VII).
Deduce the name of this acid.
........................................................................................................................ [1]
(d) Propanol reacts with methanoic acid to form the ester propyl methanoate.
CH3CH2CH2OH + HCOOH → HCOOCH2CH2CH3 + H2O 4.0
g of methanoic acid was reacted with 6.0 g of propanol.
(i)
(ii)
(iii)
Calculate the Mr of methanoic acid = ........................................
[1]
Calculate the Mr of propanol = ........................................
[1]
Determine which one is the limiting reagent. Show your reasoning.
.............................................................................................................................................
.............................................................................................................................................
....................................................................................................................................... [2]
(iv)
Calculate the maximum yield in grams of propyl methanoate, Mr = 88.
....................................................................................................................................... [1]
[Total: 17]
4
Sulfuric acid is an important acid, both in the laboratory and in industry.
Sulfuric acid is manufactured in the Contact Process. Originally, it was made by heating metal
sulfates and by burning a mixture of sulfur and potassium nitrate.
(a) Give a major use of sulfuric acid.
.............................................................................................................................................. [1]
(b) A group of naturally occurring minerals have the formula of the type FeSO4.xH2O where x is 1,
4, 5, 6 or 7. The most common of these minerals is iron(II) sulfate-7-water.
(i)
When this mineral is heated gently it dehydrates.
FeSO4.7H2O
green
FeSO4 +
pale yellow
7H2O
Describe how you could show that this reaction is reversible.
.............................................................................................................................................
.............................................................................................................................................
....................................................................................................................................... [2]
(ii)
When the iron(II) sulfate is heated strongly, further decomposition occurs.
2FeSO4(s) → Fe2O3(s) + SO2(g) + SO3(g)
The gases formed in this reaction react with water and oxygen to form sulfuric acid.
Explain how the sulfuric acid is formed.
.............................................................................................................................................
....................................................................................................................................... [2]
(iii)
A mineral of the type FeSO4.xH2O contains 37.2% of water.
Complete the calculation to determine x.
mass of one mole of H2O = 18 g
mass of water in 100 g of FeSO4.xH2O = 37.2 g
number of moles of H2O in 100 g of FeSO4.xH2O = .................
mass of FeSO4 in 100 g of FeSO4.xH2O = ................. g
mass of one mole of FeSO4 = 152 g
number of moles of FeSO4 in 100 g of FeSO4.xH2O = .................
x = .................
[4]
(c) When a mixture of sulfur and potassium nitrate is burned and the products are dissolved in
water, sulfuric acid is formed.
(i)
The sulfuric acid formed by this method is not pure. It contains another acid.
Deduce the identity of this acid.
....................................................................................................................................... [1]
(ii)
The heat causes some of the potassium nitrate to decompose.
Write the equation for the action of heat on potassium nitrate.
....................................................................................................................................... [2]
[Total: 12]
5
Compound X is a colourless liquid at room temperature.
(a) A sample of pure X was slowly heated from –5.0 °C, which is below its melting point, to 90 °C,
which is above its boiling point. Its temperature is measured every minute and the results are
represented on the graph.
F
90 °C
D
E
temperature
B
t °C
–5 °C
(i)
A
time
Complete the equation for the equilibrium present in the region BC.
X(s)
(ii)
C
....................
[1]
What is the significance of temperature t °C?
....................................................................................................................................... [1]
(iii)
What is the physical state of compound X in the region EF?
....................................................................................................................................... [1]
(iv)
What would be the difference in the region BC if an impure sample of X had been used?
....................................................................................................................................... [1]
(b) Compound X is a hydrocarbon. It contains 85.7% of carbon. The mass of one mole of X is 84 g.
(i)
What is the percentage of hydrogen in the compound ?
....................................................................................................................................... [1]
(ii)
Calculate the empirical formula of X. Show your working.
empirical formula = ................................ [3]
(iii)
What is the molecular formula of compound X?
....................................................................................................................................... [1]
[Total: 9]
1
20.0 g of small lumps of calcium carbonate and 40 cm3 of hydrochloric acid, concentration
2.0 mol / dm3, were placed in a flask on a top pan balance. The mass of the flask and contents
was recorded every minute.
cotton wool to prevent
drops of acid spray escaping
flask
40 cm3 of hydrochloric acid, 2.0 mol / dm3
20.0 g of small lumps of
calcium carbonate
balance
The mass of carbon dioxide given off was plotted against time.
mass of
carbon dioxide
0
0
time
CaCO3(s) + 2HCl (aq)  CaCl 2(aq) + H2O(l) + CO2(g)
In all the experiments mentioned in this question, the calcium carbonate was in excess.
(a)
a)
Explain how you could determine the mass of carbon dioxide given off in the first five
minutes.
.............................................................................................................................. [1]
(ii) Label the graph F where the reaction rate is the fastest, S where it is slowing down
and 0 where the rate is zero.
[2]
(iii) Explain how the shape of the graph shows where the rate is fastest, where it is
slowing down and where the rate is zero.
....................................................................................................................................
....................................................................................................................................
.............................................................................................................................. [2]
(b) Sketch on the same graph, the line which would have been obtained if 20.0 g of small
lumps of calcium carbonate and 80 cm3 of hydrochloric acid, concentration 1.0 mol / dm3,
had been used.
[2]
(c) Explain in terms of collisions between reacting particles each of the following.
(i) The reaction rate would be slower if 20.0 g of larger lumps of calcium carbonate and
40 cm3 of hydrochloric acid, concentration 2.0 mol / dm3, were used.
....................................................................................................................................
....................................................................................................................................
.............................................................................................................................. [2]
(ii) The reaction rate would be faster if the experiment was carried out at a higher
temperature.
....................................................................................................................................
....................................................................................................................................
.............................................................................................................................. [2]
(d) Calculate the maximum mass of carbon dioxide given off when 20.0 g of small lumps of
calcium carbonate react with 40 cm3 of hydrochloric acid, concentration 2.0 mol / dm3.
CaCO3(s) + 2HCl (aq)  CaCl 2(aq) + H2O(l) + CO2(g)
number of moles of HCl used =
mass of carbon dioxide = ................. g [4]
[Total: 15]
2
Soluble salts can be made by the neutralisation of an acid by a base. Insoluble salts can be
made by precipitation.
(a) The following is a brief description of the preparation of the soluble salt,
nickel(II) chloride-6-water, from the insoluble base nickel(II) carbonate.
Nickel(II) carbonate is added in small amounts to hot dilute hydrochloric acid until it is
in excess. The mixture is filtered. The filtrate is partially evaporated and then allowed to
cool until crystals of nickel(II) chloride-6-water form.
(i) Why is it necessary to use excess carbonate?
....................................................................................................................................
.............................................................................................................................. [1]
(ii) Explain why it is necessary to filter.
.............................................................................................................................. [1]
(iii) Why partially evaporate rather than evaporate to dryness?
....................................................................................................................................
.............................................................................................................................. [1]
(iv) What additional steps are needed to obtain dry crystals?
....................................................................................................................................
.............................................................................................................................. [2]
(b) Potassium chloride can be made from hydrochloric acid and potassium carbonate.
(i) Why must a different experimental method be used for this preparation?
....................................................................................................................................
.............................................................................................................................. [1]
(ii) Give a description of the different method used for this salt preparation.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
.............................................................................................................................. [4]
(c) Insoluble salts are made by precipitation. An equation for the preparation of barium
sulfate is given below.
BaCl 2(aq) + MgSO4(aq) → BaSO4(s) + MgCl 2(aq)
This reaction can be used to find x in the formula for hydrated magnesium sulfate
MgSO4.xH2O.
A known mass of hydrated magnesium sulfate, MgSO4.xH2O, was dissolved in water.
Excess aqueous barium chloride was added. The precipitate of barium sulfate was
filtered, washed and dried. Finally it was weighed.
Mass of hydrated magnesium sulfate = 1.476 g
Mass of barium sulfate formed = 1.398 g
The mass of one mole of BaSO4 = 233 g
The number of moles of BaSO4 formed = ...............
[1]
The number of moles of MgSO4.xH2O = ...............
[1]
The mass of one mole of MgSO4.xH2O = ............... g
[1
The mass of one mole of MgSO4 = 120 g
The mass of xH2O in one mole of MgSO4.xH2O = ...............
[1]
x = ...............
[1]
[Total: 15]
3
Titanium is a transition element. It is isolated by the following reactions.
titanium ore → titanium(IV) oxide → titanium(IV) chloride → titanium
TiO2
TiCl 4
Ti
(a) Why is it usually necessary to include a number in the name of the compounds of
transition elements?
..................................................................................................................................... [1]
(b) Titanium(IV) chloride is made by heating the oxide with coke and chlorine.
TiO2 + 2Cl 2
2C + O2
TiCl 4 + O2
2CO
Explain why the presence of coke ensures the maximum yield of the metal chloride.
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
(c) Explain why the change, titanium(IV) chloride to titanium, is reduction.
...........................................................................................................................................
..................................................................................................................................... [1]
(d) Complete the table which shows some of the properties of titanium and its uses.
The first line has been completed as an example.
property
soluble in molten steel
related use
making steel titanium alloys
........................................................................ making aircraft and space vehicles
resistant to corrosion, especially in sea water
...............................................................
[2]
(e) The titanium ore contains 36.8% iron, 31.6% titanium and the remainder is oxygen.
(i)
Determine the percentage of oxygen in this titanium compound.
percentage of oxygen = ........................................................................... %
(ii)
[1]
Calculate the number of moles of atoms for each element.
The number of moles of Fe is shown as an example.
number of moles of Fe = 36.8 / 56 = 0.66
number of moles of Ti = ...........................................................................................
number of moles of O = ..................................................................................... [1]
(iii)
What is the simplest ratio for the moles of atoms?
Fe
.............
:
Tii
.............
.............
[1]
(iv)
What is the formula of this titanium compound?
.............................................................................................................................. [1]
[Total: 10]
4
Soluble salts can be made using a base and an acid.
(a) Complete this method of preparing dry crystals of the soluble salt
cobalt(II) chloride-6-water from the insoluble base cobalt(II) carbonate.
Step 1
Add an excess of cobalt(II) carbonate to hot dilute hydrochloric acid.
Step 2
...........................................................................................................................................
...........................................................................................................................................
Step 3
...........................................................................................................................................
...........................................................................................................................................
Step 4
...........................................................................................................................................
..................................................................................................................................... [4]
(b) 6.0 g of cobalt(II) carbonate was added to 40 cm3 of hydrochloric acid, concentration
2.0 mol / dm3. Calculate the maximum yield of cobalt(II) chloride-6-water and show that
the cobalt(II) carbonate was in excess.
CoCO3 + 2HCl → CoCl 2 + CO2 + H2O
CoCl 2 + 6H2O → CoCl 2.6H2O
Maximum yield
Number of moles of HCl used = .........................
Number of moles of CoCl 2 formed = .........................
Number of moles of CoCl 2.6H2O formed = .........................
Mass of one mole of CoCl 2.6H2O = 238 g
Maximum yield of CoCl 2.6H2O = ......................... g
[4]
To show that cobalt(II) carbonate is in excess
Number of moles of HCl used = ......................... (use value from above)
Mass of one mole of CoCO3 = 119 g
Number of moles of CoCO3 in 6.0 g of cobalt(II) carbonate = .........................
[1]
Explain why cobalt(II) carbonate is in excess .................................................................
..................................................................................................................................... [1]
[Total: 10]
1
Crystals of sodium sulphate-10-water, Na2SO4.10H2O, are prepared by titration.
burette filled with
sulphuric acid
conical flask
25.0 cm3 of sodium hydroxide(aq)
concentration 2.24 mol / dm3
(a) 25.0 cm3 of aqueous sodium hydroxide is pipetted into a conical flask.
A few drops of an indicator are added. Using a burette, dilute sulphuric acid is slowly
added until the indicator just changes colour. The volume of acid needed to neutralise
the alkali is noted.
Suggest how you would continue the experiment to obtain pure, dry crystals of sodium
sulphate-10-water.
[4]
3
3
(b) Using 25.0 cm of aqueous sodium hydroxide, 2.24 mol / dm , 3.86 g of crystals were
obtained. Calculate the percentage yield.
2NaOH + H2SO4
Na2SO4 + 2H2O
Na2SO4 + 10H2O
Na2SO4.10H2O
Number of moles of NaOH used =
Maximum number of moles of Na2SO4.10H2O that could be formed =
Mass of one mole of Na2SO4.10H2O = 322 g
g
Maximum yield of sodium sulphate-10-water =
Percentage yield =
%
[4]
[Total: 8]
2
(a
(i) Write a symbol equation for the action of heat on zinc hydroxide.
[2]
(ii) Describe what happens when solid sodium hydroxide is heated strongly.
[1]
(b) What would be observed when copper(II) nitrate is heated?
[3]
(c) Iron(III) sulphate decomposes when heated. Calculate the mass of iron(III) oxide
formed and the volume of sulphur trioxide produced when 10.0 g of iron(III) sulphate
was heated.
Mass of one mole of Fe2(SO4)3 is 400 g.
Fe2(SO4)3 (s)
Fe2O3 (s) + 3SO3 (g)
Number of moles of Fe2(SO4)3 =
Number of moles of Fe2O3 formed =
Mass of iron(III) oxide formed =
g
Number of moles of SO3 produced =
Volume of sulphur trioxide at r.t.p. =
dm3
[5]
3
Calcium and other minerals are essential for healthy teeth and bones. Tablets can be taken
to provide these minerals.
Healthy Bones
Each tablet contains
calcium
magnesium
zinc
copper
boron
(a) Boron is a non-metal with a macromolecular structure.
(i)
What is the valency of boron?
...........................................................................
(ii)
Predict two physical properties of boron.
...................................................................................................................................
...................................................................................................................................
(iii)
Name another element and a compound that have macromolecular structures.
element …………………..
compound ………………………
(iv)
Sketch the structure of one of the above macromolecular substances.
[7]
(b) Describe the reactions, if any, of zinc and copper(II) ions with an excess of aqueous
sodium hydroxide.
(i)
zinc ions
addition of aqueous sodium hydroxide .....................................................................
...................................................................................................................................
excess sodium hydroxide ..........................................................................................
...................................................................................................................................
(ii)
copper(II) ions
addition of aqueous sodium hydroxide .....................................................................
...................................................................................................................................
excess sodium hydroxide ..........................................................................................
...............................................................................................................................[4]
(c) Each tablet contains the same number of moles of CaCO3 and MgCO3. One tablet
reacted with excess hydrochloric acid to produce 0.24 dm3 of carbon dioxide at r.t.p.
CaCO3 + 2HCl → CaCl2 + CO2 +
MgCO3 + 2HCl → MgCl2 + CO2 +
(i)
2O
Calculate how many moles of CaCO3 there are in one tablet.
=
..............
number of moles of CaCO3 and MgCO3 =
..............
=
..............
number of moles CO2
number of moles of CaCO3
(ii)
2O
[3]
Calculate the volume of hydrochloric acid, 1.0 mol / dm3, needed to react with one
tablet.
number of moles of CaCO3 and MgCO3 in one tablet
Use your answer to (c)(i).
=
..............
number of moles of HCl needed to react with one tablet =
..............
volume of hydrochloric acid, 1.0 mol / dm3, needed to
react with one tablet
..............
=
[2]
4
Sulphur dioxide, SO2, and sulphur trioxide, SO3, are the two oxides of sulphur.
(a) Sulphur dioxide can kill bacteria and has bleaching properties. Give a use of sulphur
dioxide that depends on each of these properties.
(i)
ability to kill bacteria .............................................................................................[1]
(ii)
bleaching properties .............................................................................................[1]
(b) Sulphur trioxide can be made from sulphur dioxide.
(i)
Why is this reaction important industrially?
...............................................................................................................................[1]
(ii)
Complete the word equation.
sulphur dioxide + ……………….………………………
(iii)
→
sulphur trioxide
[1]
What are the conditions for this reaction?
...................................................................................................................................
...............................................................................................................................[2]
(c) Sulphur dioxide is easily oxidised in the presence of water.
SO2 + 2H2O – 2e–
(i)
→
SO42– + 4H+
What colour change would be observed when an excess of aqueous sulphur
dioxide is added to an acidic solution of potassium manganate(VII)?
...............................................................................................................................[2]
(ii)
To aqueous sulphur dioxide, acidified barium chloride solution is added. The mixture
remains clear. When bromine is added, a thick white precipitate forms. What is the
white precipitate? Explain why it forms.
...................................................................................................................................
...............................................................................................................................[3]
(d) Sulphur dioxide reacts with chlorine in an addition reaction to form sulphuryl chloride.
SO2 + Cl2
→
SO2Cl2
8.0 g of sulphur dioxide was mixed with 14.2 g of chlorine. The mass of one mole of
SO2Cl2 is 135 g.
Calculate the mass of sulphuryl chloride formed by this mixture.
Calculate the number of moles of SO2 in the mixture = ………………
Calculate the number of moles of Cl2 in the mixture = ………………
Which reagent was not in excess? ………………………….
How many moles of SO2Cl2 were formed = ……………….
Calculate the mass of sulphuryl chloride formed = …………. g
[5]