A-LEVEL CHEMISTRY

PAPER 3
PRACTICE PAPER 3

Answer all questions
Max 90 marks
1 hour 45 minutes

	
Name		……………………………………………………………..

Mark		……../90	……....%	Grade ………
		
The first 10 multiple choice questions have already been used for AS-level resources

1.          Chlorine is a useful industrial chemical.
(a)     Chlorine gas is used in the manufacture of chlorine-containing organic compounds.
(i)      Write equations for the following steps in the mechanism for the reaction of chlorine with ethane to form chloroethane (CH3CH2Cl).
Initiation step
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First propagation step
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Second propagation step
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A termination step producing butane.
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(4)
(ii)     Give one essential condition and name the type of mechanism in this reaction of chlorine with ethane.
Essential condition .............................................................................
Type of mechanism ............................................................................
(2)
(b)     Chlorine reacts with cold water.
(i)      Write an equation for this reaction.
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(1)
(ii)     Give one large-scale application of the use of chlorine in water. Explain why it is used in this application even though chlorine is very toxic. Do not include cost.
Example of application….....................................................................
Explanation of use ..............................................................................
(2)
(iii)     Two different chlorine-containing compounds are formed when chlorine reacts with cold, dilute sodium hydroxide solution. One of these compounds is sodium chloride.
Name the other chlorine-containing compound formed.
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(1)

(c)     Chlorine is used in the extraction of bromine from seawater.
(i)      Write the simplest ionic equation for the reaction of chlorine with bromide ions.
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(1)
(ii)     Explain why bromine has a higher boiling point than chlorine.
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(2)
(Total 13 marks)
 
2.      The following pairs of compounds can be distinguished by observing what happens in test-tube reactions.
For each pair, give a suitable aqueous reagent that could be added separately to each compound.
Describe what you would observe in each case.
(a)     NaF(aq) and NaCl(aq)
Reagent ......................................................................................................
Observation with NaF(aq) ...........................................................................
Observation with NaCl(aq) ..........................................................................
(3)
(b)     BaCl2(aq) and MgCl2(aq)
Reagent .......................................................................................................
Observation with BaCl2(aq) ..........................................................................
Observation with MgCl2(aq) ..........................................................................
(3)
(c)     AgCl(s) and AgI(s)
Reagent .......................................................................................................
Observation with AgCl(s) .............................................................................
Observation with AgI(s) ...............................................................................
(3)

(d)     Butan-2-ol(l) and 2-methylpropan-2-ol(l)
Reagent …...................................................................................................
Observation with butan-2-ol(l) .....................................................................
Observation with 2-methylpropan-2-ol(l) .....................................................
(3)
(Total 12 marks)
 
3.	This question involves calculations about two strong acids and one weak acid.
All measurements were carried out at 25 °C.
(a)     A 25.0 cm3 sample of 0.0850 mol dm–3 hydrochloric acid was placed in a beaker and 100 cm3 of distilled water were added.
Calculate the pH of the new solution formed.
Give your answer to 2 decimal places.
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 (2)
(b)     HX is a weak monobasic acid.
(i)      Write an expression for the acid dissociation constant, Ka, for HX.
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(1)
(ii)     The pH of a 0.0850 mol dm–3 solution of HX is 2.79
Calculate a value for the acid dissociation constant, Ka, of this acid.
Give your answer to 3 significant figures.
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(3)

(c)     A 25.0 cm3 sample of 0.620 mol dm–3 nitric acid was placed in a beaker and 38.2 cm3 of 0.550 mol dm–3 aqueous sodium hydroxide were added.
Calculate the pH of the solution formed.
Give your answer to 2 decimal places.
The ionic product of water Kw = 1.00 × 10–14 mol2 dm–6 at 25 °C.
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 (6)
(Total 12 marks)
 
4.	Solid iron(II) ethanedioate dihydrate (FeC2O4.2H2O) has a polymeric structure.
Two repeating units in the polymer chain are shown.
 
	Each iron ion is also bonded to
two water molecules. These are
not shown in the diagram.	

(a)     Name the type of bond that is represented by the arrows.
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(1)
(b)     In terms of electrons explain how the water molecules, not shown in the diagram, form bonds to the iron.
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(2)

(c)     Predict the value of the bond angle between the two bonds to iron that are formed by these two water molecules.
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(1)
(d)     Iron(II) ethanedioate dihydrate can be analysed by titration using potassium manganate(VII) in acidic solution. In this reaction, manganate(VII) ions oxidise iron(II) ions and ethanedioate ions.
A 1.381 g sample of impure FeC2O4.2H2O was dissolved in an excess of dilute sulfuric acid and made up to 250 cm3 of solution.
25.0 cm3 of this solution decolourised 22.35 cm3 of a 0.0193 mol dm–3 solution of potassium manganate(VII).
(i)      Use the half-equations given below to calculate the reacting ratio of moles of manganate(VII) ions to moles of iron(II) ethanedioate.
 
MnO4– +  8H+  + 5e–   Mn2+  + 4H2O 

  Fe2+    Fe3+  +  e–

  C2O42–    2CO2  +  2e– 	

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(1)
(ii)     Calculate the percentage by mass of FeC2O4.2H2O in the original sample.
(If you have been unable to answer part (d)(i) you may assume that three moles of manganate(VII) ions react with seven moles of iron(II) ethanedioate. This is not the correct ratio.)
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(5)
(Total 10 marks)
 
5.	This question is about cobalt chemistry.
(a)     Consider the following reaction scheme that starts from [Co(H2O)6]2+ ions.
W and Y are ions and X is a compound.

For each of the reactions 1 to 3, identify a suitable reagent.
Identify W, X and Y and write an equation for each of reactions 1 to 3.
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 (9)

(b)     A flue-gas desulfurisation process involves the oxidation, by oxygen, of aqueous sulfate(IV) ions (SO3 2–) into aqueous sulfate(VI) ions (SO4 2–). This reaction is catalysed by Co2+ ions in an acidic aqueous solution.
Write an equation for the overall reaction of sulfate(IV) ions with oxygen to form sulfate(VI) ions.
Suggest why this overall reaction is faster in the presence of Co2+ ions.
Suggest a mechanism for the catalysed reaction by writing two equations involving Co2+ and Co3+ ions. You will need to use H+ ions and H2O to balance these two equations.
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(4)
 (Total 13 marks)

6.	Chlorine has two isotopes, 35Cl and 37Cl. The number of molecular ion peaks in the mass spectrum of a sample of Cl2 is
A       2
B       3
C       4
D       5
(Total 1 mark)

7.	A brand of fluoride tablets, recommended by a dentist to strengthen the enamel on teeth, contains 2.2 × 10−3 sodium fluoride per tablet. The total mass of fluoride ion present in 100 tablets is
A       2.2 × 10−3 ×  × 100
B       2.2 × 10−3 ×  × 100
C       2.2 × 10−3 ×  × 100
D       
(Total 1 mark)

8.	Which of these substances has permanent dipole-dipole attractions between molecules?
 
 	A	CCl4		
 	B	C2F4		
 	C	(CH3)2CO		
 	D	CO2		

(Total 1 mark)

9.	This question is about the reaction given below.
CO(g) + H2O(g)  CO2(g) + H2(g)
Enthalpy data for the reacting species are given in the table below.
 
 	Substance	CO(g)	H2O(g)	CO2(g)	H2(g)	
 	ΔH / kJ mol−1	−110	−242	−394	0	

The standard enthalpy change for this reaction of carbon monoxide and steam is
A       +42 kJ mol−1
B       −42 kJ mol−1
C       +262 kJ mol−1
D       −262 kJ mol−1
(Total 1 mark)

10.	This question is about the Maxwell–Boltzmann distribution of molecular energies in a sample of a gas shown in the following figure.
 
What does the area under the curve represent?
 
 	A	The total energy of the particles.		
 	B	The total number of particles.		
 	C	The number of particles that can react with each other.		
 	D	The total number of particles that have activation energy.		

(Total 1 mark)

11.	When one mole of ammonia is heated to a given temperature, 50 per cent of the compound dissociates and the following equilibrium is established.
NH3(g) ⇌ ½ N2 (g) +  H2 (g)
What is the total number of moles of gas present in this mixture?
A       1.5
B       2.0
C       2.5
D       3.0
(Total 1 mark)

12.	Which substance is not produced in a redox reaction when solid sodium iodide reacts with concentrated sulfuric acid?
 
 	A	H2S		
 	B	HI		
 	C	SO2		
 	D	I2		

(Total 1 mark)

13.	The number of structural isomers of molecular formula C4H9Br is
A       5
B       4
C       3
D       2
(Total 1 mark)

14.	Consider the reaction between propene and hydrogen bromide to form the major product.
Which species is formed in the mechanism of this reaction?
 
 	A	CH3–C+H–CH2Br		
 	B	CH3–CHBr–C+H2		
 	C	CH3–C+H–CH3		
 	D	CH3–CH2–C+H2		

(Total 1 mark)

15.	This question is about a method that can be used to prepare ethylamine.
CH3CH2Br  +  2NH3    CH3CH2NH2  +  NH4Br
 
Which statement about the reaction is not correct?
 
 	A	Ethylamine is a primary amine.		
 	B	The mechanism is a nucleophilic substitution.		
 	C	Using an excess of bromoethane will prevent further reaction to form a mixture of amine products.		
 	D	Ammonium bromide is an ionic compound.		

(Total 1 mark)

16.	How many structural isomers, which are esters, have the molecular formula C4H8O2?
A       2
B       3
C       4
D       5
(Total 1 mark)

17.	In a titration, 0.52 g of a diprotic acid, H2X, reacts exactly with 100 cm3 of 0.10 M sodium hydroxide.
H2X + 2NaOH → Na2X + 2H2O
The acid could be
A       ethanedioic
B       propanedioic
C       butanedioic
D       pentanedioic
(Total 1 mark)

18.	This question is about the following reaction scheme which shows the preparation of polymer P.
 
If 1.0 kg of benzene gave 0.98 kg of J, the percentage yield of J was
A       64
B       66
C       68
D       70
(Total 1 mark)

19.	Which one of the following pairs reacts to form an organic product with only 2 singlets in its proton n.m.r. spectrum?
A       ethene and bromine
B       propan-2-ol and acidified potassium dichromate(VI)
C       ethanol and concentrated sulphuric acid
D       epoxyethane and water in the presence of dilute sulphuric acid
(Total 1 mark)

20.	The percentage of iron in a sample of impure iron(II) sulphate crystals can be determined by titrating solutions, made from separate weighed samples acidified with dilute sulphuric acid, against a standard solution of potassium manganate(VII).
Which one of the following statements explains why dilute hydrochloric acid is unsuitable for use in this titration?
A       HCl will oxidise Fe2+ to Fe3+
B       Cl− will reduce Fe3+ to Fe2+
C       Cl− will reduce MnO
D       HCl is a strong acid
(Total 1 mark)

21.	The percentage of iron in a sample of impure iron(II) sulphate crystals can be determined by titrating solutions, made from separate weighed samples acidified with dilute sulphuric acid, against a standard solution of potassium manganate(VII).
Which one of the following would lead to the greatest error in the calculation of the percentage of iron(II) in the sample?
A       an error of 0.005 g made when weighing out a sample of mass 0.987 g
B       an end-point error of 0.1 cm3 in 25.0 cm3
C       an error of 5 cm3 when measuring out 25.0 cm3 of dilute sulphuric acid
D       using the average of the titration values 25.4, 25.7 and 25.9 when the correct value is 25.5 cm3
(Total 1 mark)

22.	Which one of the following statements about the reaction below is false?
[Cu(H2O)6]2+ + EDTA4−  [Cu(EDTA)]2- + 6H2O
A       [Cu(EDTA)]2− is a more stable complex than [Cu(H2O)6]2+
B       Both [Cu(H2O)6]2+ and [Cu(EDTA)]2− are octahedral complexes.
C       There is an increase in entropy when the reaction occurs.
D       There is a redox reaction.
(Total 1 mark)

23.	In which one of the following reactions is H2O2 behaving as a reducing agent?
A       H2O2 + 2I− + 2H+ → I2 + 2H2O
B       H2O2 + 2[Co(NH3)6]2+ → 2[Co(NH3)6]3+ + 2OH−
C       5H2O2 + − 2MnO + 6H+ → 2Mn2+ + 8H2O + 5O2
D       3H2O2 + 2[Cr(OH)6]3− → 2CrO + 8H2O + 2OH−
(Total 1 mark)

24.	In the table below, which one of the following complex ions has a correct shape, co-ordination number and oxidation state?
 
 	 	Complex	Shape	Co-ordination
number	Oxidation state of
central cation	
 	A	[Ag(CN)2]−	Linear	2	–1	
 	B	[CuCl4]2−	Tetrahedral	4	–2	
 	C	[Cr(C2O4)3]3−	Octahedral	3	+3	
 	D	[Cu(NH3)4(H2O)2]2+	Octahedral	6	+2	

(Total 1 mark)

25.	Use your knowledge of the chemistry of transition metals to predict which of the following will convert [Mn(H2O)6]2+ into MnO
A       an acid and a reducing agent
B       an acid and an oxidising agent
C       an alkali and a reducing agent
D       an alkali and an oxidising agent
(Total 1 mark)

26.	This question is about the reaction given below.
    CO(g) + H2O(g)   CO2(g) + H2(g)
Enthalpy data for the reacting species are given in the table below.
 
 	Substance	CO(g)	H2O(g)	CO2(g)	H2(g)	
 	ΔH / kJ mol−1	−110	−242	−394	0	

Which one of the following statements is not correct?
A       The value of Kp changes when the temperature changes.
B       The activation energy decreases when the temperature is increased.
C       The entropy change is more positive when the water is liquid rather than gaseous.
D       The enthalpy change is more positive when the water is liquid rather than gaseous.
(Total 1 mark)

27.	The vanadium does not have an oxidation state of +3 in
A       [V(H2O)6]3+
B       [V(C2O4)3]3−
C       [V(OH)3(H2O)3]
D       [VCl4]3−
(Total 1 mark)

28.	Propanone can be reduced to form an alcohol. A functional group isomer of the alcohol formed is
A       CH3CH2CH2OH
B       CH3CH2CHO
C       CH3OCH2CH3
D       CH3COCH3
(Total 1 mark)

29.	Which one of the following is a pair of functional group isomers?
A       CH3COOCH2CH3 and CH3CH2COOCH3
B       (CH3)2CHCH(CH3)2 and (CH3)3CCH2CH3
C       CH3CH2OCH3 and (CH3)2CHOH
D       ClCH2CH2CH=CH2 and CH3CH=CHCH2Cl
(Total 1 mark)

30.	In which one of the following reactions is a heterogeneous catalyst not used?
A       N2 + 3H2 → 2NH3
B       CO + NO → CO2 +  N2
C       CO2 + C → 2CO
D       SO2 +  O2 → SO3
(Total 1 mark)

31.	Which one of the following is a correct procedure for isolating a sample of hydrated copper(II) sulphate from a mixture of hydrated copper(II) sulphate and barium sulphate?
A        filter, crystallise filtrate, dry the crystals
B        filter, dry the solid on the filter paper
C        add water, filter, dry the solid left on the filter paper
D        add water, filter, crystallise filtrate, dry the crystals 
(Total 1 mark)

32.	The following information concerns the equilibrium gas-phase synthesis of methanol.
CO(g) + 2H2(g)  CH3OH(g)
At equilibrium, when the temperature is 68 °C, the total pressure is 1.70 MPa.
The number of moles of CO, H2 and CH3OH present are 0.160, 0.320 and 0.180, respectively.
Thermodynamic data are given below.
 
 	Substance	ΔH / kJ mol−1
	S / J K-1 mol-1	
 	CO(g)	−110	198	
 	H2(g)	0	131	
 	CH3OH(g)	−201	240	

The standard entropy change for this reaction is
A       −220 J K−1 mol−1
B       +220 J K−1 mol−1
C       −89 J K−1 mol−1
D       +89 J K−1 mol−1
(Total 1 mark)

33.	An aqueous solution contains 4.0 g of sodium hydroxide in 250 cm3 of solution.
(Kw = 1.00 × 10−14 mol2 dm−6)
The pH of the solution is
A       13.0
B       13.3
C       13.6
D       13.9
(Total 1 mark)

34.	Which one of the following pairs of reagents reacts to form an organic product that shows only 2 peaks in its proton n.m.r. spectrum?
A       butan-2-ol and acidified potassium dichromate(VI)
B       ethanoyl chloride and methanol
C       propanoic acid and ethanol in the presence of concentrated sulphuric acid
D       ethene and hydrogen in the presence of nickel
(Total 1 mark)

35.	In which one of the following reactions does the metal species undergo reduction?
A       MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
B       [Cu(H2O)6]2++ 4Cl− → [CuCl4]2− + 6H2O
C       Cr2O + 2OH−  → 2CrO + H2O
D       TiO2 + 2C + 2Cl2 → TiCl4 + 2CO
(Total 1 mark)