Practice exam 4 · 32 pages · 120 marks · 15 minutes reading, 2 hours 30 minutes writing

Chemistry – Practice exam 4

Carbohydrate gels, a spacecraft fuel cell, ethene hydration, nickel plating, 1-bromobutane, identifying C3H8O, olive and coconut oils, and magnesium with acid.

Marks by area of study

Unit 3 AOS 1: 29 marksUnit 3 AOS 2: 34 marksUnit 4 AOS 1: 20 marksUnit 4 AOS 2: 28 marksSustainability: 3 marksKey science skills: 8 marks

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

Q	Context	Marks
1	Endurance athletes often consume carbohydrate gels during races	12
2	Crewed spacecraft have used alkaline hydrogen–oxygen fuel cells as their main power source	10
3	In some countries, industrial ethanol is produced by the direct hydration of ethene.	12
4	A steel bicycle part with a total surface area of 150 cm2 is to be electroplated with nickel	10
5	1-Bromobutane, CH3CH2CH2CH2Br, is used as a starting material in organic synthesis	11
6	Compound X has the molecular formula C3H8O	11
7	Olive oil and coconut oil are both mixtures of triglycerides	12
8	Students investigated the rate of reaction between magnesium ribbon and hydrochloric acid	12

Section A: what each question tests (30 marks)

Q	Key knowledge	Area of study
1	renewability and carbon neutrality of biofuels	Unit 3 AOS 1
2	energy from mass of fuel using ΔHc	Unit 3 AOS 1
3	mass–volume stoichiometry at SLC	Unit 3 AOS 1
4	temperature–time graphs in calorimetry	Unit 3 AOS 1
5	energy content of protein: metabolism v combustion	Unit 3 AOS 1
6	oxidants and reductants in the electrochemical series	Unit 3 AOS 1
7	half-equations in acidic conditions	Unit 3 AOS 1
8	predicting galvanic cell reactions	Unit 3 AOS 1
9	design features of fuel cells	Unit 3 AOS 1
10	collision theory: pressure	Unit 3 AOS 2
11	equilibrium constants from an ICE table	Unit 3 AOS 2
12	adding an inert gas at constant volume	Unit 3 AOS 2
13	effect of catalysts on equilibrium	Unit 3 AOS 2
14	products of aqueous electrolysis	Unit 3 AOS 2
15	discharge and recharge of secondary cells	Unit 3 AOS 2
16	Faraday’s laws: charge on the ion	Unit 3 AOS 2
17	repeatability and reproducibility	Units 3–4 Key science skills
18	safety in organic synthesis	Units 3–4 Key science skills
19	naming haloalkanes with two substituents	Unit 4 AOS 1
20	interpreting skeletal formulas	Unit 4 AOS 1
21	solubility of alcohols in water	Unit 4 AOS 1
22	hydrolysis of esters	Unit 4 AOS 1
23	percentage yield	Unit 4 AOS 1
24	green chemistry principles	Units 3–4 Cross-study
25	fractional distillation	Unit 4 AOS 2
26	choosing an indicator	Unit 4 AOS 2
27	limitations of retention time as evidence	Unit 4 AOS 2
28	¹H NMR chemical shifts	Unit 4 AOS 2
29	polarity of amino acid side chains	Unit 4 AOS 2
30	effect of pH on enzyme activity	Unit 4 AOS 2