Practice exam 8 · 28 pages · 120 marks · 15 minutes reading, 2 hours 30 minutes writing

Chemistry – Practice exam 8

Wood pellets, alkaline batteries, nitrogen monoxide and catalytic converters, PEM electrolysers, malic acid, identifying a bromoalkane, detergent enzymes and testing Faraday’s laws.

Marks by area of study

Unit 3 AOS 1: 30 marksUnit 3 AOS 2: 31 marksUnit 4 AOS 1: 13 marksUnit 4 AOS 2: 30 marksSustainability: 8 marksKey science skills: 9 marks

Section B: short-answer and extended-response questions (90 marks)

Q	Context	Marks
1	Wood pellets are used as a renewable fuel for home heating	11
2	An alkaline AA battery contains powdered zinc as the anode and manganese(IV) oxide, MnO2, mixed with graphite	11
3	Nitrogen monoxide, NO, is an air pollutant formed in car engines, where air is heated to very high temperature	11
4	A proton-exchange-membrane (PEM) electrolyser splits pure water into hydrogen and oxygen	11
5	Malic acid gives apples their sour taste	11
6	A liquid, V, has the molecular formula C4H9Br	11
7	‘Biological’ laundry detergents contain enzymes, including proteases, which hydrolyse proteins, and lipases, w	11
8	Students tested Faraday’s laws by electrolysing copper(II) sulfate solution with two copper electrodes	13

Section A: what each question tests (30 marks)

Q	Key knowledge	Area of study
1	composition and energy content of biogas	Unit 3 AOS 1
2	energy from gas volumes	Unit 3 AOS 1
3	limiting reactants with gas volumes	Unit 3 AOS 1
4	bomb calorimetry	Unit 3 AOS 1
5	energy content of food groups	Unit 3 AOS 1
6	identifying oxidants	Unit 3 AOS 1
7	half-equations in alkaline conditions	Unit 3 AOS 1
8	electron flow in galvanic cells	Unit 3 AOS 1
9	catalysts in fuel cells	Unit 3 AOS 1
10	catalysts and collision theory	Unit 3 AOS 2
11	equilibrium expressions in aqueous solution	Unit 3 AOS 2
12	Le Châtelier: pressure and colour	Unit 3 AOS 2
13	electrolysis of aqueous solutions	Unit 3 AOS 2
14	design of lithium-ion cells	Unit 3 AOS 2
15	Faraday’s laws: current	Unit 3 AOS 2
16	drawing valid conclusions	Units 3–4 Key science skills
17	systematic errors and accuracy	Units 3–4 Key science skills
18	naming esters	Unit 4 AOS 1
19	types of structural isomer	Unit 4 AOS 1
20	branching and boiling point	Unit 4 AOS 1
21	addition reactions of alkenes	Unit 4 AOS 1
22	improving yield in organic synthesis	Unit 4 AOS 1
23	calculating atom economy	Unit 4 AOS 1
24	end point and equivalence point	Unit 4 AOS 2
25	acid–base stoichiometry with a hydrated primary standard	Unit 4 AOS 2
26	conditions for comparing retention times	Unit 4 AOS 2
27	fragmentation in mass spectra	Unit 4 AOS 2
28	IR identification of compounds with two functional groups	Unit 4 AOS 2
29	¹H NMR environments	Unit 4 AOS 2
30	primary structure of proteins	Unit 4 AOS 2