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Support Materials

National Assessment Bank pack

Revised Chemistry (Higher)

Principles to Production FE4D 12/NAB001

SCQF level 6

Publication date: December 2011

Publication code: FE4D 12/NAB001

The information in this publication may be reproduced to support SQA qualifications.This publication must not be reproduced for commercial or trade purposes. Thismaterial is for use by teaching staff only.

Published by the Scottish Qualifications AuthorityThe Optima Building, 58 Robertson Street, Glasgow, G2 8DQLowden, 24 Wester Shawfair, Dalkeith, Midlothian, EH22 1LFD

www.sqa.org.uk

© Scottish Qualifications Authority 2011

http://www.sqa.org.uk/http://www.sqa.org.uk/http://www.sqa.org.uk/

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Scottish Qualifications AuthorityNational Assessment Bank/FE4D 12/001 V1Revised Chemistry (Higher): Principles to Production December 2011

History of changes

Versionnumber

Date Description Authorised by

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Scottish Qualifications Authority 1 National Assessment Bank/FE4D 12/001 V1Revised Chemistry (Higher): Principles to Production December 2011

Introduction

Security and confidentiality of Support Materials

This material is intended solely for the purpose of assessment of candidates againstNational Unit standards in SQA approved centres and must not be released prior toexamination/practical test or distributed more widely for any other purpose.

Support Materials are distributed only to SQA approved centres and may bedownloaded from SQA’s secure website by authorised personnel. For addedsecurity, SQA discourages the downloading of this material for; the maintenance ofpaper-based libraries, stockpiling ahead of assessment events and saving toportable storage devices and laptop computers.

The assessment and marking information in this publication can be used or adapted

by staff in approved SQA centres subject to the guidelines above. Adapted materialsmust be verified prior to use and stored securely within the presenting centre.

In addition to a centre’s own security procedures, any suspected breach of the abovemust be reported immediately to SQA’s Business Development and CustomerSupport team marked ‘Security breach — Support Materials’.

Copyright

The information in this publication may be reproduced in support of SQAqualifications. Where the publication includes materials from sources other than SQA

(secondary copyright), this material should only be reproduced for the purposes ofexamination or assessment. If it needs to be reproduced for any other purpose it isthe centre’s responsibility to obtain the necessary copyright clearance. SQA’sSupport Materials team may be able to direct you to the secondary sources.

Every effort has been made to contact copyright holders and SQA apologises if anyhave been overlooked.

General information

Before using this National Assessment Bank pack centres should read the relevant

Unit specification which details the standard of performance expected of candidates.It is important to ensure that this pack is used in a context appropriate to the Unitand, if applicable, the associated Group Award. A copy of the Unit specification canbe found on SQA’s website www.sqa.org.uk.

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Assessment conditions

Arrangements documents and subject guides refer to assessment being carried outunder controlled conditions to ensure reliability and credibility. For the purposes ofinternal assessment, this means that the assessment evidence should be compiled

under supervision to ensure that it is the candidate’s own work.

Timing and duration

The duration of the end of Unit assessment for Outcomes 1 and 2 is 45 minutes.

Instruments of Assessment

This Unit has two Outcomes. Outcome 1 and 2 are assessed by a holistic end of Unittest. It is expected that the learning and teaching process will involve somediagnostic assessment and review of learning before the candidate attempts the endof Unit test.

Quality assurance

Centres should retain assessment evidence and internal verification records. Unitsare subject to external verification by SQA.

Re-assessment

Time is allowed within Units for assessment and re-assessment of Outcomes. Where

candidates have not attained the standard necessary to pass a particular Outcomeor Outcomes, they should have the opportunity to be re-assessed. SQA’s advice isthat there should normally be one Unit re-assessment opportunity, or in exceptionalcircumstances two. In some cases candidates will be required to resubmit originalwork which has been revised to take account of earlier weaknesses. In other cases,candidates will be required to undertake a new instrument designed to assess theparticular Outcome(s) in which they were unsuccessful. In all cases, evidence fromthe original assessment should be used for formative purposes prior tore-assessment.

Outcomes 1 and 2

The recommended method of re-assessment is for candidates to re-sit another entiretest to allow them to demonstrate success. A number of different assessments areavailable.

Cut-off scores

A cut-off score of 60% should be used for this Unit assessment, in this case 18 out of30.

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Estimates and appeals

Estimates

Valid evidence of attainment could be generated through the use of an assessmentinstrument, such as a prelim, based on the work from at least two Units in theCourse, which replicates, as far as possible, the standard, format, duration andsecurity of SQA’s Question Paper.

Evidence produced only from NABs will not provide an accurate estimate. Theassessment tasks should comprise questions that are integrative and set in contextsmore complex and demanding than those associated with NABs.

Appeals

Evidence must cover all Units of the Course and have the same breadth of coverage

of Course content as SQA’s Question Paper and relate to the Course GradeDescriptions. While a prelim paper is not mandatory, it is an indicator of likelycandidate performance in the external examination when pressure of time andretention of learning are significant factors. Evidence should replicate as far aspossible the standard, format, duration and security of SQA’s Question Paper.

Evidence for the appeal could include:

A prelim which covers all Units and replicates the standard, format, duration andsecurity of SQA’s Question Paper .or

A prelim which covers a minimum of two Units of the Course and replicates thestandard, format, duration and security of SQA’s Question Paper plus anadditional test, which provides evidence of attainment against the Course GradeDesciptions for a grade A award, covering the third Unit, preferably with someintegration of work from the other two Units.or

A prelim which covers a minimum of two Units of the Course and replicates thestandard, format, duration and security of SQA’s Question Paper plus a highscoring NAB for the third Unit to support an appeal for a grade C, but not anappeal for grades A or B.

Evidence produced from NABs alone will not be sufficiently compelling for appeals.

Disabled candidates and/or those with additional support needs

The additional support needs of individual candidates should be taken into accountwhen planning learning experiences, selecting assessment instruments, orconsidering whether any reasonable adjustments may be required. Further advicecan be found on our website www.sqa.org.uk/assessmentarrangements.

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Section 1— Instrument of Assessment

Outcomes 1 and 2 are assessed by a single holistic test which has a total of 30marks. The ratio of the marks allocated to Outcome 1 and Outcome 2 isapproximately 4:1. Thus Outcome 1 will have questions worth a total ofapproximately 24 marks and Outcome 2 will have questions worth a total ofapproximately 6 marks.

Each assessment has a ‘Map of Outcomes and Performance Criteria’ which showsthe mapping of questions to individual Outcomes and Performance Criteria. Theconstruction of an assessment paper must ensure that all the Performance Criteriaare covered.

The marks are not distributed equally between the Performance Criteria, but toensure reliability across different assessment versions a ‘recommended range of

marks’ has been used. The distribution of marks is partly due to the nature of thesubject. Also a mark for a question or a part of a question is usually allocated to oneelement of the grid only depending on its dominant Performance Criterion. Howeverthere may be instances where the marks for a part question are split between criteriasince the question assesses different Outcomes or Performance Criteria.

The most appropriate assessment instrument has been designed to produceevidence of achievement. This assessment, while addressing all the relevantOutcomes and Performance Criteria, may not readily provide specific, discreteevidence that each Performance Criterion has been met. However, the threshold ofattainment (pass mark) for each test is deemed to provide satisfactory evidence that

each achievement of the Outcomes and Performance Criteria has beendemonstrated or could be inferred.

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Revised Chemistry (Higher)— Map of Outcomes and PerformanceCriteria

Principles to Production

Outcome 1 Outcome 2

PC (a) PC(b) PC(c) PC(a) PC(b)

1 Getting most fromcostly reactants

(a) Factors affecting thedesign

Q1

(b) Calculationsinvolving 100 %yield

Q5Q6Q16

(c) Calculations

involving solutions

Q7

Q14(a)

(d) Reversible reactions Q2

(e) Altering equilibriumposition

Q13(b) Q8Q13(c)(i)

Q13(c)(ii)

(f) % yield and atomeconomy

Q17(a)Q17(b)

Q17(c) Q17(c)

(g) Excess Q14(b)

2 Controlling the

rate(a) Collision theory Q14(c)

(b) Reaction profiles Q13(a)(i) Q9

(c) Temperature andkinetic energy

Q3 Q10

(d) Catalysts Q13(a)(ii)

3 Chemical energy

(a) Enthalpy Q11 Q7

(b) Enthalpies ofcombustion

Q4

(c) Hess’s Law Q12

(d) Bond enthalpies Q18(a)Q18(b)

4 Chemicalanalysis/qualitycontrol

(a) Chromatography

(b) Volumetric titration Q15(a) Q15(b)

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Revised Chemistry (Higher)

Unit title— Principles to Production

Unit Assessment for Outcomes 1 and 2 — Answer sheet

Time— 45 minutes

Name of centre

Name of candidate

Date of Assessment

Mark

Pass 18/30

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Part A

This part of the paper consists of 12 fixed-response questions and is worth 12marks.

In questions 1 –4, choose the most suitable word from the following list to completethe sentence.

biodegradable concentration constant equal

gram mole temperature toxic

1 One of the environmental considerations in the design of an industrial process

is to minimise the use of substances.

2 In a reversible reaction equilibrium is reached when the concentration of

reactants and products are .

3 The number of particles with energy greater than the activation energy can be

used to explain the effect of on reaction rate.

4 The enthalpy of combustion of a substance is the enthalpy change when one

of the substance burns completely in oxygen.

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Questions 5 –12 are multiple choice questions.

5 NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)

The mass of silver chloride precipitated when 0·05 mol NaCl(aq) is added to

excess AgNO3(aq) is:

A 4·250 g

B 7·170 g

C 8·495 g

D 143·4 g

6 The complete combustion of propane produces carbon dioxide and water.

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(ℓ)

What volume of carbon dioxide gas, in cm3, would be obtained if 10 cm3 ofpropane gas was completely burned in excess oxygen gas?

A 10

B 20

C 30

D 40

7 When 0·025 mol of hydrochloric acid reacts with 0·025 mol of sodium hydroxide1·45 kJ of energy was given out.

HCl(aq) + NaOH(aq) NaCl(aq) + H2O(ℓ)

The energy, in kJ mol-1

, given out when one mole of hydrochloric acid reacts withone mole of sodium hydroxide is:

A 29

B 58

C 87

D 116

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8 For the reaction:

CH4(g) + H2O(g) CO(g) + 3H2(g) H = +206 kJ

which two conditions favour the formation of hydrogen?

A High temperature, low pressure

B High temperature, high pressure

C Low temperature, low pressure

D Low temperature, high pressure

9 The potential energy diagram for a chemical reaction is shown below:

What is the enthalpy change, in kJ mol-1, for the reaction?

A -66

B -227

C -361

D -427

Potential

energy/kJ mol-1

-227

0

134

200

Reaction pathway

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10 A reaction was carried out at four different temperatures.

The table below shows the times taken for the reaction to go to completion.

Temperature/°C 20 30 40 50

Time(s) 60 30 14 5

The results show that:

A the reaction is endothermic

B the activation energy increases with increasing temperature

C the rate of the reaction is directly proportional to the temperature

D a small rise in temperature results in a large increase in reaction rate.

11 The combustion of a fuel is found to raise the temperature of 500 cm3 of water by20 °C.

The energy transferred to the water is

A 41·8 kJ

B 83·6 kJ

C 8360 kJ

D 41800 kJ

12 The enthalpy changes, H, for two reactions are shown.

C(s) + O2(g) CO2(g) H = -395·2 kJ mol-1

CO(g) + ½O2(g) CO2(g) H = -284·3 kJ mol-1

What is enthalpy change for the following reaction?

C(s) + ½O2(g) CO(g)

A -679·5 kJ mol-1

B -110·9 kJ mol-1

C +110·9 kJ mol-1

D +679·5 kJ mol-1

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Part B Marks

This part of the paper consists of six questions and is worth 18 marks.

13 Ammonia is made by the Harber Process.

N2(g) + 3H2(g) 2NH3(g)

(a) The potential energy diagram for the reaction is shown.

Sketch the above diagram onto your answer paper. On yoursketch:

(i) clearly label the activation energy for the forward reaction; 1

(ii) use a dotted line to show potential energy diagram obtainedwhen a catalyst is used in the reaction. 1

(b) What effect does the use of a catalyst have on the position ofequilibrium? 1

(c) Ammonia gas is very soluble in water.

NH3(g) + (aq) NH3(aq)

(i) Heating the solution produces ammonia gas.

What effect does heating have on the position of equilibrium? 1

(ii) Ammonia gas is less dense than air and cannot be collectedby displacement of water because it is too soluble.

Draw a diagram showing a suitable method of collecting thegas. 1

P o t e n t i a l e n e r g y

Reaction pathway

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Marks

14 Magnesium reacts with sulfuric acid according to the equation:

Mg(s) + H2SO4(aq) MgSO4(aq) + H2(g)

In an experiment a student added 0·1 mol of magnesium powder to100 cm3 of 0·1 mol l-1 sulfuric acid.

(a) Calculate the number of moles in 100 cm3 of 0·1 mol 1-1 sulfuricacid. 1

(b) Which reactant is in excess? 1

(c) The volume of hydrogen produced over time in this reaction wasmeasured and is shown on the graph.

The student repeated the experiment using 0·1 mol of magnesiumin a lump.

Sketch the above graph onto your answer paper and add anothercurve to the graph to show the results of the second experiment. 1

15 In a redox titration, 2∙6 x 10-4 mol of cerium(IV) ions (Ce4+) reacted

with oxalic acid (H2C2O4). The equation for the reaction that took placewas

2Ce4+(aq) + H2C2O4(aq) → 2Ce3+(aq) + 2H+(aq) + 2CO2(g)

(yellow) (colourless) (colourless)

(a) How many moles of oxalic acid react with 2·6 x 10-4 mol of cerium(IV) ions? 1

(b) An indicator did not have to be added to identify the end-point of thistitration.

Give a reason for this. 1

Powder

300

0

75

150

225

18016014012010080604020

Time/s

Volume of

hydrogen

produced

/cm3

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Marks

16 Calculate the volume, in litres, of 4 g of methane gas, CH4(g).

Take the molar volume to be 23 litres mol-1. 2

Show your working clearly.

17 Ethanol, C2H5OH, can be dehydrated to produce ethene, C2H4, usingexcess sulfuric acid. Ethoxyethane, C2H5OC2H5, is produced as a by-product. The equation for the reaction is shown.

4C2H5OH(ℓ) 2C2H4 (g) + C2H5OC2H5(ℓ) + 3H2O(ℓ)

(GFM 46) (GFM 28)

In this process, 328 kg of ethanol produces an actual yield of 42 kg ofethene.

(a) Calculate the atom economy for the process. 1

(b) (i) Calculate the theoretical yield of ethene from 328 kg ethanol. 1

(ii) Calculate the percentage yield of ethene produced. 1

(c) Give a reason why a reaction with a high percentage yield mayhave a low atom economy. 1

18 Xenon reacts with fluorine to form the compound XeF6.

Xe(g) + 3F2(g) XeF6(g)

(a) How much energy, in kJ, is needed to convert 3 moles of fluorinemolecules into 6 moles of fluorine atoms?

You may wish to use page 9 of the data booklet. 1

(b) The Xe –F bond enthalpy is -160 kJ mol-1. Use this plus youranswer to part (a) to calculate the enthalpy for the reaction. 1

Total marks: 30

Pass mark: 18

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Section 2— Marking information

(There are no ½ marks awarded)

Part A Marks

1 Toxic 1 2 Constant 1 3 Temperature 1 4 Mole 1 5 B 1 6 C 1 7 B 1 8 A 1 9 C 1 10 D 1

11 A 1 12 B 1

Part B

13 (a) (i) 1

(ii) 1

(b) No effect 1

(c) (i) Moves it to the side of reactants/to the left 1

(ii) Diagram of gas collection by downward displacement of air orgas syringe. 1

14 (a) 0·01 1

(b) Magnesium 1

(c) Slope less steep than powder and finishing at the same finalvolume 1

Activation

energy

catalyst

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Scottish Qualifications Authority 15 National Assessment Bank/FE4D 12/001 V1R i d Ch i t (Hi h ) P i i l t P d ti D b 2011

Marks

15 (a) 1·3 x 10-4 mol 1

(b) Accept correct answer relating to colour change in mixture 1

16 16 g occupies 23 l4 g occupies 5·75 l (unit not needed) 2

17 (a) 12·8 1

(b) (i) 199·65 kg (200 kg) 1

(ii) 21(%) 1

(c) Large quantities of unwanted by-products formed. 1

18 (a) 465 kJ (0 marks if no unit given) 1

(b) -495 kJ mol-1 1

Total marks: 30

unit 3 nab1

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