1 Check that the answer sheet provided is for Chemistry Advanced Higher (Section A).
2 For this section of the examination you must use an HB pencil and, where necessary, an eraser.
3 Check that the answer sheet you have been given has your name, date of birth, SCN (Scottish Candidate Number) and Centre Name printed on it.
Do not change any of these details.
4 If any of this information is wrong, tell the Invigilator immediately.
5 If this information is correct, print your name and seat number in the boxes provided.
6 The answer to each question is either A, B, C or D. Decide what your answer is, then, using your pencil, put a horizontal line in the space provided (see sample question below).
7 There is only one correct answer to each question.
8 Any rough working should be done on the question paper or the rough working sheet, not on your answer sheet.
9 At the end of the exam, put the answer sheet for Section A inside the front cover of your answer book.
Sample Question
To show that the ink in a ball-pen consists of a mixture of dyes, the method of separation would be
A chromatography
B fractional distillation
C fractional crystallisation
D filtration.
The correct answer is A—chromatography. The answer A has been clearly marked in pencil with a horizontal line (see below).
Changing an answer
If you decide to change your answer, carefully erase your first answer and using your pencil, fill in the answer you want. The answer below has been changed to D.
A
A
B
B
C
C
D
D
Page three[X012/13/02]
1. Which equation can be used to represent the second ionisation energy of the diatomic element, X?
A X2(g) → X22+(g) + 2e–
B ½X2(g) → X2+(g) + 2e–
C X+(g) → X2+(g) + e–
D X(g) → X2+(g) + 2e–
2. Which of the following lists electromagnetic radiation bands in order of increasing frequency?
A Ultraviolet, visible, infra-red, radio
B Radio, infra-red, visible, ultraviolet
C Radio, microwave, ultraviolet, visible
D Visible, ultraviolet, X-ray, microwave
3. Using information from the Data Booklet which one of the following metal salts will emit radiation of the highest frequency when placed in a Bunsen flame?
A Copper(II) sulphate
B Potassium chloride
C Barium chloride
D Lithium sulphate
4. Which of the following indicators transmits only the lower frequencies of the visible spectrum at low pH?
Indicator Colour in acid Colour in alkali A Violet Red
B Green Blue
C Yellow Violet
D Red Yellow
5. When electrons occupy degenerate orbitals, they do so in such a way as to maximise the number of parallel spins. This statement is known as
A the Pauli exclusion principle
B Heisenberg’s uncertainty principle
C the aufbau principle
D Hund’s rule.
6. Which of the following represents the configuration of the highest energy electrons in an atom of a Group III element in the ground state?
A 3s23p1
B 3s23p3
C 4s23d1
D 4s24p3
7. Which of the following analytical techniques would be most suitable to determine quantitatively the concentration of sodium ions in a urine sample?
A Mass spectrometry
B Infra-red spectroscopy
C Atomic emission spectroscopy
D Proton nuclear magnetic resonance spectroscopy
8. Which of the following represents a valid Lewis electron dot diagram for ozone, O3?
A
B
C
D
[Turn over
O
OO
O
O
OO
O
O
O O
O
Page four[X012/13/02]
9. Which of the following substances contains a dative covalent bond?
A NH3
B NCl3
C NH4Cl
D CH3NH2
10. Which of the following molecules has the greatest number of non-bonding electron pairs (lone pairs)?
A
B
C
D
11. The following diagram represents a square-planar structure.
Where and represent bonding electron pairs
and represents a non-bonding electron pair (lone pair).
Which of the following species could have the structure shown above?
A SF4
B NH4+
C XeF4
D AlH4–
12.
The graph shows how the electrical conductivity varies with temperature in
A a metal
B an ionic solid
C a semiconductor
D a superconductor.
13. Which of the following compounds contains hydride ions?
A NH3
B HCl
C H2S
D CaH2
14. In which of the following reactions does the oxidation state of copper neither increase nor decrease?
A
B
C
D
15. 100 cm3 of 0·500 mol l–1 AgNO3(aq) is reacted with excess CaCl2(aq).
What mass of precipitate forms?
A 7·17 g
B 8·95 g
C 12·6 g
D 14·3 g
H
C
H
H Cl
H
C
H
H O H
H
CH O
H
C
H
H
H
H N
Temperature
Electrical conductivity
Zn + CuSO4 → ZnSO4 + Cu
CuSO4 + 4NH3 → [Cu(NH3)4]SO4
FeCl2 + CuCl2 → FeCl3 + CuCl
Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2
Page five[X012/13/02]
16. When a salt, formula Ni(H2O)6.K2(SO4)2, is dissolved in water, the solution contains the ions Ni(H2O)6
2+, K+ and SO42–.
The total number of moles of ions in one litre of 0·01 mol l–1 solution is
A 0·01
B 0·03
C 0·05
D 0·10.
17. What volume of 0·2 mol l –1 potassium sulphate is required to make, by dilution with water, one litre of a solution with a potassium ion concentration of 0·1 mol l –1?
A 100 cm3
B 250 cm3
C 400 cm3
D 500 cm3
18. Phosphoric acid is a weak acid and undergoes partial dissociation according to the equation
H3PO4 ! H2PO4– + H+
The position of equilibrium would be shifted to the right by the addition of
A a catalyst
B sulphuric acid
C sodium hydroxide
D sodium dihydrogenphosphate.
19. Caffeine can be extracted from coffee dissolved in water using the solvent dichloromethane (CH2Cl2).
caffeine(aq) ! caffeine(CH2Cl2)
Which of the following, when increased, will change the value of the partition coefficient for this equilibrium?
A Temperature
B Mass of coffee
C Volume of water
D Volume of dichloromethane
20. Substance X is distributed between equal volumes of two immiscible liquids as shown in the diagram. The number of dots represents the relative distribution of X in the two liquids at equilibrium.
X(aq) ! X(hexane)
The partition coefficient for this system is
A 0·46
B 0·50
C 2·00
D 2·17.
21. Which of the following decreases when an aqueous solution of ethanoic acid is diluted?
A pH
B [H+]
C pKa
D The degree of dissociation
22. Iodide ions are oxidised by acidified nitrite ions according to the equation
2NO2– + 2I– + 4H+ → 2NO + I2 + 2H2O
Addition of sodium ethanoate to the reaction mixture slows down the formation of iodine.
The most likely explanation for this effect is that ethanoate ions
A remove iodine
B reduce the concentration of iodide ions
C react with nitrite ions
D react with hydrogen ions.
hexane
water
[Turn over
Page six[X012/13/02]
23. Which of the following indicators should be used in the titration of potassium hydroxide solution with ethanoic acid solution?
A Phenolphthalein, pH range 8·0 – 9·8
B Bromothymol blue, pH range 6·0 – 7·6
C Methyl red, pH range 4·2 – 6·2
D Methyl orange, pH range 3·1 – 4·4
24. The following diagram illustrates the catalysed and uncatalysed reaction pathways for a reversible reaction.
The activation energy for the reverse uncatalysed reaction is given by
A s – r
B p + s
C q – p
D p + r.
25. The element X can exist in two forms, as X≡X, or as X8 with the following cubic structure.
The X—X bond dissociation enthalpy is 163 kJ mol–1.
The X≡X bond dissociation enthalpy is 944 kJ mol–1.
Which of the following is the value of ∆H, in kJ mol–1, for the reaction
X8(g) → 4X2(g)?
A –2472
B –1820
C +1820
D +2472
Energy
Reactants
Products
r
qp
s
Reaction pathway
X
X
X
X
X
X
X
X
26. Which of the following sets of information would enable the bond enthalpy of a C=C double bond to be calculated?
Enthalpy of Enthalpy of Enthalpy of (Mean) bond formation of combustion of sublimation of enthalpy of
A ethene ethene C —H, H—H
B benzene benzene C —H, H—H
C ethene carbon C —H, H—H
D benzene carbon C —H, H—H
Page seven[X012/13/02]
27. In which of the following changes will there be an increase in entropy?
A CO2(g) → CO2(s)
B Combustion of ethanol
C Hydrogenation of ethene
D Phenylethene → poly(phenylethene)
28. One mole of which of the following chlorides would have the greatest entropy at 750 °C?
A Sodium chloride
B Calcium chloride
C Potassium chloride
D Magnesium chloride
29. The conversion of butanoic acid into butan-1-ol is an example of
A elimination
B substitution
C oxidation
D reduction.
30.
Which line in the table is correct for the types of reaction taking place at ① , ② and ③?
Reaction ① Reaction ② Reaction ③A substitution elimination substitution
B substitution reduction substitution
C addition reduction condensation
D addition elimination substitution
31. Bromine reacts with propene to produce 1,2-dibromopropane.
A possible intermediate in the reaction is
A
B
C
D
32. Which of the following represents an initiation step in a chain reaction?
A Cl2 →
B CH3 3 → C2H6
C CH4 → CH3
D CH3 2 → CH3
33. Which of the following compounds would be expected to have the highest boiling point?
A Pentanal
B Pentan-2-ol
C Pentan-2-one
D Ethoxypropane
[Turn over
propan-1-ol
1-chloropropane
methoxypropanepropene
①
② ③
Br
Br
C
H
H
C
H
H C
H
H
C
H
H
C
H
H
Br
C
H
H
C
H
H
C
H
H C
H
H
Br
C
H
H
C
H
H C
H
H
Page eight[X012/13/02]
34. Which line in the table shows a general formula which does not match the homologous series?
General formula
Homologous series
A CnH2nO alkanals
B CnH2nO2 alkanoic acids
C CnH2n+2O alkanols
D CnH2nO ethers
35. The Williamson synthesis for the preparation of unsymmetrical ethers (ROR') starting with an alcohol and a halogenoalkane is summarised in the general equations:
Step 1: ROH + Na → RO–Na+ + ½H2
Step 2: RO–Na+ + R' X → ROR' + Na+X–
Using propan-2-ol and 2-chlorobutane, the unsymmetrical ether formed would be
A CH3CH2CH2OCH(CH3)CH2CH3
B CH3CH2CH2OCH2CH2CH2CH3
C CH3CH(CH3)OCH2CH2CH2CH3
D CH3CH(CH3)OCH(CH3)CH2CH3
36. Which of the following is the strongest base?
A CH3CH2OH
B OH
C CH3CH2NH2
D NH2
37. Phenylamine reacts with hydrochloric acid.
The products are
A
B
C
D
38.
Which species initially attacks the benzene molecule in the above reaction?
A NO3–
B NO2+
C HSO4–
D NO2
HNO3
H2SO4
NO2
NH
+ HCl
H
NCl
+ H2
H
Cl
+ NH3
NH
+ ½H2
H
Cl
NH
H
+ Cl_
+H
Page nine[X012/13/02]
39.
The above reaction is an example of
A addition
B oxidation
C elimination
D substitution.
40. Most medicines work by binding to receptors.
Receptors are usually
A nucleophiles
B electrophiles
C free radicals
D protein molecules.
[Turn over for SECTION B on Page ten
[END OF SECTION A]
Candidates are reminded that the answer sheet for Section A MUST be placed INSIDE the front cover of your answer book.
Marks
1
1
(2)
1
3
(4)
Page ten[X012/13/02]
SECTION B
60 marks are available in this section of the paper.
All answers must be written clearly and legibly in ink.
1. (a) Name a dopant which could be added to germanium to make a p-type semiconductor.
(b) What is the charge carrier in a p-type semiconductor?
2. Burning magnesium continues to burn when placed in a gas jar of carbon dioxide according to the equation
2Mg(s) + CO2(g) → 2MgO(s) + C(s)
(a) Using the values from the table above, calculate ∆S° for the reaction.
(b) Using the information below and your answer to (a), calculate ∆G° for the burning of magnesium in carbon dioxide.
Mg(s) + ½O2(g) → MgO(s) ∆H° = – 493 kJ mol–1
C(s) + O2(g) → CO2(g) ∆H° = –394 kJ mol–1
burning spoon
carbon dioxide
gas jar
magnesium
Substance S°/JK–1 mol–1
Mg(s)
CO2(g)
MgO(s)
C(s)
33·0
214
27·0
5·70
3. The Born-Haber cycle diagram shows the theoretical process involved in the formation of rubidium chloride from the elements rubidium and chlorine.
(a) Write the equation which represents the standard enthalpy of formation of rubidium chloride.
(b) Use the Data Booklet to find the value for enthalpy change ∆Hf.
(c) What name is given to the enthalpy change represented by ∆Hg?
(d) Calculate the value for enthalpy change ∆Hg.
4. In a PPA the manganese content of a steel paper clip is determined by converting the manganese into purple permanganate ions, the concentration of which is measured using colorimetry.
At the start of the activity, a calibration graph has to be drawn.
(a) What data must be collected to allow the calibration graph to be drawn?
(b) Which colour of filter or wavelength of light should be used in this procedure?
(c) A weighed sample of the paper clip is dissolved in 2 mol l–1 nitric acid in a beaker covered with a watch glass which is placed in a fume cupboard because a toxic gas is produced.
Name this toxic gas.
(d) Colorimetry is not used to determine potassium content because potassium ions are not coloured. The concentration of potassium ions in a compound can be determined using atomic absorption spectroscopy at a wavelength of 405 nm.
Calculate the energy, in kJ mol–1, of this radiation.
Marks
1
1
1
1
(4)
1
1
1
2
(5)
Page eleven[X012/13/02] [Turn over
Rb+(g) + e– + Cl(g)
Rb+Cl–(s)
Rb(g) + Cl(g)
Rb(g) + ½Cl2(g)
Rb(s) + ½Cl2(g)
Rb+(g) + Cl–(g)
409 kJ∆H
121·5 kJ∆H
81 kJ∆H
– 435 kJ∆H
∆H
∆H
e
d
c
h
f
g
5.
The absorption spectrum of a solution of sodium tetrachlorocobaltate(II) is shown above.
(a) Predict the most likely colour of the solution.
(b) Write the electronic configuration for a cobalt(II) ion in terms of s, p and d orbitals.
(c) Write the formula for the tetrachlorocobaltate(II) ion.
6. Propanoic acid is a weak acid. Sodium propanoate is a salt which can be formed from it. Both propanoic acid and sodium propanoate can be used as mould inhibitors.
(a) Calculate the pH of 0·10 mol l–1 propanoic acid solution.
(b) 0·20 moles of sodium propanoate are added to 100 cm3 of the 0·10 mol l–1 solution of propanoic acid.
Calculate the pH of the buffer solution formed.
Marks
1
1
1
(3)
2
2
(4)
Page twelve[X012/13/02]
400 450 500 550 600 650 700Wavelength/nm
Absorbance
1·0
0
7. (a) Calculate the emf of a Cr(s)|Cr3+(aq)||Fe2+(aq)|Fe(s) cell operating under standard conditions.
(b) Calculate the free energy change, ∆G°, in kJ per mole of chromium, for this cell reaction.
(c) Use the Ellingham diagram below to explain whether zinc or aluminium should be chosen to extract chromium from chromium oxide.
(c) Calculate a value for the rate constant, k, including the appropriate units.
(d) There are four structural isomers of C4H9Br.
(i) From the above results, which isomer is most likely to have been used?
(ii) Explain your answer to (d)(i).
Marks
1
1
2
1
1
(6)
Page fourteen[X012/13/02]
Marks
1
2
(3)
Page fifteen[X012/13/02]
9. Nickel(II) ions react quantitatively with dimethylglyoxime (C4H8O2N2) forming a complex which precipitates out as a red solid. The equation for the reaction and the structure of the complex are shown below.
Ni2+ + 2C4H8O2N2 → Ni(C4H7O2N2)2 + 2H+
(a) What is the coordination number of nickel in the complex?
(b) When 0·968 g of an impure sample of nickel(II) sulphate, NiSO4.7H2O, was dissolved in water and reacted with dimethylglyoxime, 0·942 g of the red precipitate was formed.
Calculate the percentage, by mass, of nickel in the impure sample of nickel(II) sulphate.
HO
H3C
H3C
CH3
CH3
O
O O
NC
C
C
C
N
N N
H
Ni
Relative formula mass = 288·7
[Turn over
Page sixteen[X012/13/02]
10. A student devised the following reaction sequence.
(a) What type of reaction is taking place in step c?
(b) What experimental condition would be required in step d?
(c) Draw a structural formula for product X.
(d) What type of reaction is taking place in step f?
(e) Draw a structural formula for product Y.
Marks
1
1
1
1
1
(5)
CH3CH2Cl/AlCl3 Cl2 KOH(aq)
KOH in ethanol
Cl2
CH2CH2Cl
c d e
f
g
CH2CH3
X
Y
CHCH2
11. Methylamphetamine (also known as “speed”) and caffeine are stimulants.
A “designer drug” with a structure related to methylamphetamine is ecstasy. Ecstasy tablets are sometimes contaminated with a substance called 4-MTA.
(a) Caffeine contains more than one “amide” functional group.
Draw the structure of caffeine and circle one of the “amide” functional groups.
(b) Which of the four molecules contains a primary amine functional group?
(c) Draw the structure of the pharmacaphore common to methylamphetamine, ecstasy and 4-MTA.
12. In a PPA, cyclohexene is prepared from cyclohexanol using a dehydrating agent.
(a) Which dehydrating agent is used in the PPA?
(b) (i) When the reactants have been heated gently for about 15 to 20 minutes, the mixture is allowed to cool. Separation of the product is carried out by adding saturated sodium chloride solution to the reaction mixture and vigorously shaking them together for about a minute and allowing them to settle and form two layers.
Why is saturated sodium chloride solution used rather than water?
(ii) Which piece of apparatus is used in this part of the procedure?
(c) The identity of the product can be verified by using infra-red spectroscopy.
Predict one difference that would be observed between the infra-red spectra of cyclohexene and cyclohexanol.
Marks
1
1
1
(3)
1
1
1
1
(4)
Page seventeen[X012/13/02]
CH2
CH3
CH3CHN
H
methylamphetamine
ecstasy
caffeine
4-MTA
N
N
CH3
CH3
N
N
O
O
CH3
CH2
H2C
O
O CH3
CH3CHN
H
CH2
H3C S CH3
HCHN
H
[Turn over
13. The diagram below shows a reaction sequence starting from compound A which is pentan-2-ol (C5H12O).
Compound B can exist as two geometric isomers.
Compound C is pent-1-ene.
Compound D is the oxidation product of compound A.
(a) Name and draw the structural formulae for the two geometric isomers of compound B.
(b) Name compound D.
(c) Compound E is a cyanohydrin.
(i) Name the type of reaction occurring when D is converted into E.
(ii) Draw a structural formula for compound E.
(d) Name or draw a structural formula for compound F.
Marks
2
1
1
1
1
(6)
Page eighteen[X012/13/02]
H+(aq)/MnO4–(aq) HCN
C5H12O C5H10O C6H11NO
(C5H10) (C6H12O3)
ConcentratedH2SO4
H+(aq)
A ED
B + C F
Page nineteen[X012/13/02]
14. 5·00 g of an organic compound A was burned completely producing 11·89 g of CO2 and 6·08 g of H2O as the only products.
(a) Using the information above, calculate the empirical formula for compound A.
(b) The infra-red spectrum of compound A is shown below.
Which bond is responsible for the peak at 1140 cm–1?
(c) The mass spectrum of compound A shows the molecular ion to have a mass/charge ratio of 74. Deduce the molecular formula of compound A.
(d) The proton nmr spectrum of compound A is shown below.
Using all the above information, deduce the structural formula for compound A.
Finalised Marking Instructions � Scottish Qualifications Authority 2013 The information in this publication may be reproduced to support SQA qualifications only on a non-commercial basis. If it is to be used for any other purposes written permission must be obtained from SQA’s NQ Assessment team. Where the publication includes materials from sources other than SQA (secondary copyright), this material should only be reproduced for the purposes of examination or assessment. If it needs to be reproduced for any other purpose it is the centre’s responsibility to obtain the necessary copyright clearance. SQA’s NQ Assessment team may be able to direct you to the secondary sources. These Marking Instructions have been prepared by Examination Teams for use by SQA Appointed Markers when marking External Course Assessments. This publication must not be reproduced for commercial or trade purposes.
Part One: General Marking Principles for Chemistry Advanced Higher This information is provided to help you understand the general principles you must apply when marking candidate responses to questions in this Paper. These principles must be read in conjunction with the specific Marking Instructions for each question. (a) Marks for each candidate response must always be assigned in line with these general marking
principles and the specific Marking Instructions for the relevant question. If a specific candidate response does not seem to be covered by either the principles or detailed Marking Instructions, and you are uncertain how to assess it, you must seek guidance from your Team Leader/Principal Assessor.
(b) Marking should always be positive ie, marks should be awarded for what is correct and not
deducted for errors or omissions. GENERAL MARKING ADVICE: Chemistry Advanced Higher The marking schemes are written to assist in determining the “minimal acceptable answer” rather than listing every possible correct and incorrect answer. The following notes are offered to support Markers in making judgements on candidates’ evidence, and apply to marking both end of unit assessments and course assessments. General information for markers The general comments given below should be considered during all marking. 1 Marks should not be deducted for incorrect spelling or loose language as long as the meaning of
the word(s) is conveyed. Example: Answers like ‘distilling’ (for ‘distillation’) and ‘it gets hotter’ (for ‘the temperature
rises’) should be accepted. 2 A right answer followed by a wrong answer should be treated as a cancelling error and no marks
should be given. Example: What is the colour of universal indicator in acid solution? The answer ‘red, blue’ gains no marks. 3 If a right answer is followed by additional information which does not conflict, the additional
information should be ignored, whether correct or not. Example: Why can the tube not be made of copper?
If the correct answer is related to a low melting point, and the candidate’s answer is ‘It has a low melting point and is coloured grey’ this would not be treated as a cancelling error.
4 Full marks should be awarded for the correct answer to a calculation on its own whether or not
the various steps are shown unless the question is structured or working is specifically asked for.
5 A mark should be deducted in a calculation for each arithmetic slip unless stated otherwise in
the marking scheme. No marks should be deducted for incorrect or missing units at intermediate stages in a calculation.
Page 3
6 A mark should be deducted for incorrect or missing units unless stated otherwise in the marking scheme. Please note, for example, that KJ mol-1 is not acceptable for kJ mol-1 and a mark should be deducted.
7 Where a wrong numerical answer (already penalised) is carried forward to another step, no
further penalty is incurred provided the result is used correctly. 8 No mark is given for the solution of an equation which is based on a wrong principle.
Example: Use the information in the table to calculate the standard entropy change for the reaction:
C2H2 + 2HCl CH2ClCH2Cl
Compound Sº/J K−1 mol−1
C2H2 201
HCl 187
CH2ClCH2Cl 208
Using 'Sº = Sº reactants - Sº products would gain zero marks. 9 No marks are given for the description of the wrong experiment. 10 Full marks should be given for correct information conveyed by a sketch or diagram in place of a
written description or explanation. 11 In a structural formula, if one hydrogen atom is missing but the bond is shown, no marks are
deducted. Examples: Would not be penalised as the structural formula for ethyl ethanoate. If the bond is also missing, then zero marks should be awarded. Example:
H C C C O C
H
H
H O
H H H
H
C C H C O C
H H
H H
O
H
Page 4
12 If a structural formula is asked for, CH3– and CH3CH2 – are acceptable as methyl and ethyl
groups respectively. 13 With structures involving an –OH or an –NH2 group, no mark should be awarded if the ‘O’ or
‘N’ are not bonded to a carbon, ie OH–CH2 and NH2–CH2. 14 When drawing structural formulae, no mark should be awarded if the bond points to the ‘wrong’
atom, eg 15 A symbol or correct formula should be accepted in place of a name unless stated otherwise in
the marking scheme. 16 When formulae of ionic compounds are given as answers it will only be necessary to show ion
charges if these have been specifically asked for. However, if ion charges are shown, they must be correct. If incorrect charges are shown, no marks should be awarded.
17 If an answer comes directly from the text of the question, no marks should be given. Example: A student found that 0·05 mol of propane, C3H8 burned to give 82·4 kJ of energy. C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(ℓ) Name the kind of enthalpy change which the student measured. No marks should be given for ‘burning’ since the word ‘burned’ appears in the
text. 18 A guiding principle in marking is to give credit for (partially) correct chemistry rather than to
look for reasons not to give marks. Example 1: The structure of a hydrocarbon found in petrol is shown below.
Name the hydrocarbon.
Although not completely correct, the answer, ‘3, methyl-hexane’ would gain the full mark ie wrong use of commas and dashes.
C C
OH
CH3 CH2 CH CH2 CH3 CH2
CH3
Page 5
Example 2: A student measured the pH of four carboxylic acids to find out how their strength is
related to the number of chlorine atoms in the molecule. The results are shown.
How is the strength of the acids related to the number of chlorine atoms in the
molecule? Again, although not completely correct, an answer like ‘the more Cl2, the stronger
the acid’ should gain the full mark. Example 3: Why does the (catalytic) converter have a honeycomb structure? A response like ‘to make it work’ may be correct but it is not a chemical answer and
the mark should not be given.
Page 6
Part Two: Marking Instructions for each Question Section A
Question Acceptable Answer/s Question Acceptable Answer/s 1 C 16 C 2 B 17 B 3 A 18 C 4 D 19 A 5 D 20 D 6 A 21 B 7 C 22 D 8 A 23 A 9 C 24 B 10 B 25 B 11 C 26 C 12 C 27 B 13 D 28 D 14 B 29 D 15 A 30 A
Page 7
Question Acceptable Answer/s
31 D 32 A 33 B 34 D 35 D 36 C 37 D 38 B 39 A 40 D
Page 8
Section B
Question Acceptable Answer Mark
Unacceptable answer
1 a Name a dopant which could be added to germanium to
make a p-type semiconductor. Correct name and wrong symbol
Wrong name and correct symbol (cancelling errors)
Any group 3 element,
or boron, aluminium, gallium, indium or thallium or correct symbol
1 Group 3
1 b What is the charge carrier in a p-type semiconductor? Positive hole(s)
+ holes +ve holes Electron deficient holes
1 Positive or + or +ve (cancelling errors apply) Hole(s) Electron(s)
(2)
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2 Burning magnesium continues to burn when placed in a gas
2 a Using the values from the table above, calculate 'So for the
reaction.
−220·3 J K−1 (mol−1) or −0·2203 kJ K−1 (mol−1)
−220 J K−1 (mol−1) or −0·220 kJ K−1 (mol−1) or −0·22 kJ K−1 (mol−1) Max of 5 sig figs
1 No units J k−1 mol−1 or j K−1 mol−1 (but give candidates benefit of the doubt if unsure) negative sign missing
2 b Using the information below and your answer to (a),
calculate 'Go for the burning of magnesium in carbon dioxide.
Mg(s) + ½ O2(g) → MgO(s) 'Ho = −493 kJ mol−1
C(s) + O2(g) → CO2(g) 'Ho = −394 kJ mol−1
Correct follow through from wrong answer in (a) can get 3 marks in (b)
'Ho = −592 (kJ mol−1) or −296 (kJ mol−1) 1
'Go = 'Ho − T'So 1 = −526·35 kJ (mol−1) or kJ) (Accept −526 (kJ mol−1), −526·4 kJ mol−1) 1 (Also accept, −263, −263·2, −263·18 with correct units as final answer) Accept final answer in Joules if correct and allow 6 sig figs in this case (526350 or 526351 J)
3 'Go = 'Ho + T'So or any incorrect relationship (lose 2 marks) 6 sig figs – lose 1 mark −526·00 or 526·3
(4)
gas jar
magnesium burning spoon
carbon dioxide
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3 The Born-Haber cycle diagram shows the theoretical
process involved in the formation of rubidium chloride from the elements rubidium and chlorine.
3 a Write the equation which represents the standard enthalpy of formation of rubidium chloride.
Rb(s) + ½ Cl2(g) Æ Rb+Cl–(s) or RbCl(s)
1 Multiple of equation. Equation without state symbols.
3 b Use the Data Booklet to find the value for enthalpy
change 'H 4
−349 kJ mol−1 or −349 kJ
1 Answer without units.
Rb+(g) + e- + Cl(g)
Rb+Cl-(s)
Rb(g) + ½Cl2(g)
Rb(s) + ½Cl2(g)
Rb(g) + Cl(g)Rb+(g) + Cl-(g)
3
2
1
6
4
5
409 kJ
121.5 kJ
81 kJ
-435 kJ
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3 c What name is given to the enthalpy change represented by
'H 5 ? Lattice breaking
Lattice (formation) (enthalpy)
Lattice Lattice energy Crystal lattice
1
3 d Calculate the value for enthalpy change 'H 5. −697·5 kJ (mol−1)
Follow through from wrong answer in (b) by −value for(b) – 1046·5 = gives correct follow through answer.
1 +697·5
(4)
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4 In a PPA the manganese content of a steel paper clip is
determined by converting the manganese into purple permanganate ions, the concentration of which is measured using colorimetry. At the start of the activity, a calibration graph has to be drawn.
4 a What data must be collected to allow the calibration graph
to be drawn?
A series of standard solutions of different concentrations
of KMnO4 is made up and their absorbances measured. Absorbances of permanganate solutions of known concentrations/variety of concentrations (must mention permanganate or manganate or purple solutions) Accept absorbancy/absorption/transmittance/transmission
1 Intensity of radiation/adsorption Measure absorbance of solutions of known concentration (must mention permanganate or manganate)
4 b Which colour of filter or wavelength of light should be
used in this procedure? Complementary colour
If wavelength given then units are required
Correct wavelength followed by an incorrect colour such as red
Green or 500 to 560 nm (Accept blue-green or green-yellow) Green followed by incorrect wavelength would not be cancelling error
1
4 c A weighed sample of the paper clip is dissolved in
2 mol l–1 nitric acid in a beaker covered with a watch glass which is placed in a fume cupboard because a toxic gas is produced. Name this toxic gas.
Nitrous oxide, N2O Nitrogen oxide or oxides of nitrogen (on its own)
nitric oxide or mixture. Correct formulae eg NO, NO2, N2O4
1
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4 d Colorimetry is not used to determine potassium content
because potassium ions are not coloured. The concentration of potassium ions in a compound can be determined using atomic absorption spectroscopy at a wavelength of 405 nm. Calculate the energy, in kJ mol−1, of this radiation.
E = O
Lhc or E =
O1000Lhc
1
= 296 or 295·6 or 295·64 or 295·65 (kJ mol−1) 1
2 295 or 296·3 6 sig figs
(5)
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5
The absorption spectrum of a solution of sodium
tetrachlorocobaltate(II) is shown above.
5 a Predict the most likely colour of the solution. Blue or green or blue/green or cyan or turquoise
1 Red etc
5 b Write the electronic configuration for a cobalt(II) ion in
terms of s, p and d orbitals.
1s2 2s2 2p6 3s2 3p6 3d7 or [Ne] 3s2 3p6 3d7 or correct
answer in terms of orbital box notation with all the orbitals labelled correctly Accept 4so with otherwise correct answer
1 [Ar] 3d7
5 c Write the formula for the tetrachlorocobaltate(II) ion. [Co2+(Cl−)4]2−
[Co(Cl)4]2− or [CoCl4]2− or CoCl4
2− Co(Cl)4
2− or [(Cl)4Co]2−
Shape of brackets unimportant −2 in place of 2−
1
(3)
(II) given in formula Overall charge 2+ (Cl)4Co2−
0
1.0
Absorbance
Wavelength/nm400 450 500 550 600 650 700
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6 Propanoic acid is a weak acid. Sodium propanoate is a
salt which can be formed from it. Both propanoic acid and sodium propanoate can be used as mould inhibitors.
6 a Calculate the pH of 0·10 mol l−1 propanoic acid solution. pH = ½ pKa − ½ log c 1
= 2·935 or 2·94 or 2·9 1 Max of 4 sig figs
2 Wrong relationship = 0 marks 2·93
6 b 0·20 moles of sodium propanoate are added to 100 cm3 of
the 0·10 mol l−1 solution of propanoic acid. Calculate the pH of the buffer solution formed.
pH = pKa − log[salt][acid]
1
= 6·171 or 6·17 or 6·2 1
2
(4)
Wrong relationship = 0 marks
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7 a Calculate the emf of a Cr(s)׀Cr3+(aq)‖Fe2+(aq)׀Fe(s) cell
operating under standard conditions.
Emf = 0·74 − 0·44 = 0·30 V or 0·3 V
1 No units −0·3V
7 b Calculate the free energy change, ΔGo, in kJ per mole of
chromium, for this cell reaction.
ΔGo = −nFEo 1
= −3 × 96500 × 0·3 (J per mole Cr) 1 (follow through from incorrect answer in (a)) = −86·9 (kJ per mole Cr) 1 (or −87 kJ or −86·85 but not −86·8) (−57·9 = 2/3 using n = 2) (−28·95 = 2/3 using n = 1) (−173·7 = 2/3 using n = 6) [These answers assume correct answer to (a)] (Accept ΔGo = −n F e for 1 mark unless candidate goes on to substitute charge on an electron for e)
3 ΔGo = nFEo (deduct 1 mark)
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7 c Use the Ellingham diagram below to explain whether zinc
or aluminium should be chosen to extract chromium from chromium oxide.
7 c Aluminium because ΣΔGo is negative for the reactions
2/3 Cr2O3 Æ 4/3Cr + O2 + 4/3Al + O2 Æ 2/3Al2O3 or Overall ΔGo is negative for the (redox) reaction: 2/3Cr2O3 + 4/3Al Æ 4/3Cr + 2/3Al2O3
Correct answer in terms of overall free energy change for the reaction
1
(5)
Aluminium is more reactive than chromium. Aluminium is above chromium in the ecs. “the lower one always extracts the higher one” “lower graph stays as written and higher graph is reversed.” “anti-clockwise rule” applies in Ellingham diagram.?
0
0 200 400 600 800 1000 1200
Temperature/ºC
1400 1600 1800 2000 2200
-100
-200
-300
-400
-500
-600
-700
-800
-900
-1000
-1100
2Zn + O2
Cr + O2 2O34
32
3
Al + O2 Al2O34
32
3
-1 O2
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8 A kinetics study was carried out on the reaction between a
halogenoalkane, C4H9Br, and aqueous sodium hydroxide.
C4H9Br + NaOH → C4H9OH + NaBr The following results were obtained. [C4H9Br]/mol l−1 [NaOH]/mol l−1 Initial Rate/mol l−1s−1
8·0 × 10−4 0·10 0·15 1·6 × 10−3 0·10 0·30 1·6 × 10−3 0·20 0·30 3·2 × 10−3 0·40 0·60 8 a What is the order of reaction with respect to 8 a i the halogenoalkane
First or 1
ii the sodium hydroxide? Zero or 0 or no order
1
8 b Write the rate equation for the reaction. Rate = k[C4H9Br] or Rate = k[C4H9Br]1 [NaOH]o
(accept correct follow on from wrong answers in (a)
1 Round brackets (0) No marks if K used in place of k
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8 c Calculate a value for the rate constant, k, including the
appropriate units.
k =Rate/[C4H9Br] = 0·15/8·0 × 10−4 = 187·5 s−1 1
1 mark for correct units. Accept 188 and 190 s−1 1 (Don’t penalise for K in place of k) Units must follow on from relationship used in (a) and/or (b) s–1 = 1 mark no matter answer given to (a) or (b) Correct follow through from (a) or (b)
2 Any wrong units, deduct 1 mark even if already lost 2 marks for units previously – except if correct due to follow through.
8 d There are four structural isomers of C4H9Br. 8 d i From the above results, which isomer is most likely to
have been used?
2-bromomethylpropane or 2-bromo-2-methylpropane
Accept 2-methyl-2-bromopropane (ignore dashes and commas) Any correct structural formula would be acceptable Accept “the tertiary isomer”/the tertiary one/tertiary structure
1 Cancelling errors apply if correct structure and wrong name or vice-versa but accept “methy” as a slip if the structure is correct But if only the name is given then do not accept errors such as “brom” or “methy” 2-methylbromopropane
8 d ii Explain your answer to (d)(i). Correct explanation in terms of Stability of carbocation or
Steric hindrance
1
(6)
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9 Nickel(II) ions react quantitatively with dimethylglyoxime
(C4H8O2N2) forming a complex which precipitates out as a red solid. The equation for the reaction and the structure of the complex are shown below.
9 a What is the coordination number of nickel in the
complex?
4 or four or iv or IV
1
9 b When 0·968 g of an impure sample of nickel(II) sulphate,
NiSO4.7H2O, was dissolved in water and reacted with dimethylglyoxime, 0·942 g of the red precipitate was formed. Calculate the percentage, by mass, of nickel in the impure sample of nickel(II) sulphate.
Mass of nickel in DMG complex
= 0·942 × (58·7/288·7) = 0·1915 g or 0·192 g 1 % Ni in impure salt = (0·1915/0·968) × 100 = 19·8 (%) 1 (Accept 19·79 % and 19·786 % and 19·835 % or 19·83 %) (Deduct 1 mark per error up to a maximum of 2 marks) (19·73 = 1 mark only – rounded 0·1915 to 0·191)
2
20·9 % (% Ni in pure salt) 20·3 % use of 0·968 instead of 0·942 in first line Use of AN in place of RAM (0)
(3)
HO
H 3C
H 3C
CH 3
CH 3
O
O O
NC
C
C
C
N
N N
H
Ni
Relat ive formula mass- 288.7
Ni2+ + 2C4H8O2N2 4H7O2N2)2 + 2H+
Relative formula mass = 288·7
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10 A student devised the following reaction sequence.
10 a What type of reaction is taking place in step 1 ? Electrophilic substitution
10 b What experimental condition would be required in step
step 2 ? Electromagnetic radiation
Light/UV radiation/radiation of correct wavelength/UV/
visible light/camera flash
1
CH3CH2Cl/AlCl 3
CH2CH3
CHCH 2
Cl2
CH2CH2Cl
Cl2 KOH(aq)
KOH in ethanol
X3
4
5
21
Y
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10 c Draw a structural formula for product X. CH2CH2OH
1 C2H4OH
Accept Kekule structure for the phenyl group Accept C6H5CH2CH2OH/benzene ring showing H’s
Ring missing or no alternate double/single bonds
10 d What type of reaction is taking place in step 4 ? (base induced) elimination,
1 Acid induced elimination
10 e Draw a structural formula for product Y. 1 H H
Cl C C Cl CHClCH2Cl
H or or C6H5CHClCH2Cl
C2H3Cl2
(5)
Ring missing or no alternate double/single bonds (0) marks unless already penalised in (c)
C6H5CCl2CH3
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11 Methylamphetamine (also known as “speed”) and caffeine
are stimulants. A “designer drug” with a structure related to methylamphetamine is ecstasy. Ecstasy tablets are sometimes contaminated with a substance called 4-MTA.
11 a Caffeine contains more than one “amide” functional
group. Draw the structure of caffeine and circle one of the “amide” functional groups. Allow minor slip in the structure of caffeine
Any one of the three amide functional group shown 1
Not necessary for CH3 to be included in the circle but
there must be a bond coming from the N and part of that bond must be within the circle
CH 2
CH 3
CH 3CHN
H
Methylamphetamine
N
N
CH 3
CH 3
N
N
O
O
CH 3
caffeine
CH 2
H2CO
O CH 3
CH 3CHN
H
ecstasy
CH 2
H3C S CH 3
HCHN
H
4-MTA
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11 b Which of the four molecules contains a primary amine
functional group?
4-MTA 1 11 c Draw the structure of the pharmacaphore common to
methylamphetamine, ecstasy and 4-MTA.
H
CH2 N
CH
CH3
1
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12 In a PPA, cyclohexene is prepared from cyclohexanol
using a dehydrating agent.
12 a Which dehydrating agent is used in the PPA? (Concentrated) phosphoric acid/orthophosphoric acid
1
12 b i When the reactants have been heated gently for about 15
to 20 minutes, the mixture is allowed to cool. Separation of the product is carried out by adding saturated sodium chloride solution to the reaction mixture and vigorously shaking them together for about a minute allowing them to settle and form two layers. Why is saturated sodium chloride solution used rather than water?
It is denser than water.
The layers separate more quickly. The layers separate better. The layers settle more quickly. The aqueous solution is more polar (than water) To get a better separation
1 It works better Get a better yield
12 b ii Which piece of apparatus is used in this part of the
12 c The identity of the product can be verified by using infra-
red spectroscopy. Predict one difference that would be observed between the infra-red spectra of cyclohexene and cyclohexanol.
Presence of:
C=C stretch or peak or absorbance/1620 to 1680 cm−1 in cyclohexene. C–H stretch or peak or absorbance/3095 to 3010 cm−1 in cyclohexene. O–H stretch/3200 to 3650 cm−1 in cyclohexanol. Accept the absence of these in the other compound.
1 Units must be given with values except for those who have already been penalised twice for wrong/incorrect/ missing units
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13 The diagram below shows a reaction sequence starting from
compound A which is pentan-2-ol (C5H12O).
13 a Compound B can exist as two geometric isomers. Compound C is pent-l-ene. Compound D is the oxidation product of compound A. Name and draw the structural formulae for the two geometric isomers of compound B.
cis-pent-2-ene 1
2
One only given but with correct structure and wrong name = 0 Both structures correct but names wrong way round = 1 out of 2 Only one structure given but with wrong name (0)
trans-pent-2-ene 1 Two correct structures, no names = 1 Two correct names, no structures = 1 Don’t penalise for bonds at 90o rather than 120o and accept CH3 in place of H3C
C5H12O
A D E
FB + C
H+(aq)/MnO4-(aq)
C5H10O
(C5H10)
C6H11NO
H+(aq)ConsentratedH2SO4
(C6H12O3)
HCN
C H
CHC C
H
H
2
3
5
C HCHC C
H H
23 5
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Pent-2-one Penta-2-one
13 b Name compound D. Pentan-2-one.
1
13 c Compound E is a cyanohydrin. 13 c i Name the type of reaction occurring when D is converted into
E.
(nucleophilic) addition.
1 Electrophilic addition
13 c ii Draw a structural formula for compound E.
CH3 C CH2 CH2 CH3
OH
C N or shortened SF with CN and (CH2)2CH3 but not with C3H7 (Accept correct follow through from incorrect answer to (b)
1
13 d Name or draw a structural formula for compound F. 2-hydroxy-2-methylpentanoic acid or
CH3 C CH2 CH2 CH3
OH
COHO
Accept COOH or CO2H and (CH2)2CH3 but not C3H7 nor (C2H4)CH3 (Accept correct follow through from incorrect answer to (c)
1
(6)
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14 5·00 g of an organic compound A was burned
completely producing 11·89 g of CO2 and 6·08 g of H2O as the only products.
14 a Using the information above, calculate the empirical
formula for compound A.
Mass of C = (12/44 × 11·89) = 3·243 g
Mass of H = (2/18 × 6·08) = 0·676 g So mass of O = 5·00 −3·243 −0·676 = 1·081 g 1 C : H : O 3·243 : 0·676 : 1·081 Ratio of moles 0·270 : 0·676 : 0·0676 4 : 10 : 1 1 Empirical formula C4H10O 1
3 Correct answer, no working = 1 mark
14 b The infra-red spectrum of compound A is shown below.
Which bond is responsible for the peak at 1140 cm−1? C-O (stretch)
1
4000
20
40
60
Transmittance/%
Wavenumber/cm-1
80
100
3500 300 2500 2000 1500 1000 500
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14 c The mass spectrum of compound A shows the molecular
ion to have a mass/charge ratio of 74. Deduce the molecular formula of compound A.
C4H10O (elements can be in any order)
1
14 d The proton nmr spectrum of compound A is shown below.
Using all the above information, deduce the structural formula for compound A.
C C O
C
C
H
H
H H
HH
H
H
H
H
1
(accept shortened structural formula of ethoxyethane)
