Q1
ORIGINAL
An instant cold pack falls from to when its chemicals mix. Classify the process and describe the direction of energy transfer.
[2 marks]
Total for this question: 2
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AQA GCSE Chemistry · Topic 4.5
Energy changes questions
Practice questions covering energy changes from this specification. Every question below is the real AQA question as it is printed on the paper, with its mark scheme.
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6 questions on Energy changes, each with its mark scheme and worked method. Reveal the answer when you have had a go.
- Q2ORIGINALA reaction mixture starts at and reaches . State whether the reaction is exothermic or endothermic.
[1 mark]
Total for this question: 1
- Q3ORIGINALProfile X has products below its reactants. Profile Y has products above its reactants. Identify the reaction type shown by each profile.
[2 marks]
Total for this question: 2
- Q4ORIGINALUse the equation and these bond energies in : , , in carbon dioxide , and . Calculate the overall energy change.
[4 marks]
Total for this question: 4
- Q5ORIGINALSimple cells using the same electrolyte give these voltages: zinc-copper , zinc-iron and iron-copper . Choose the electrode pair for the largest voltage and explain what the data suggest about electrode reactivity.
[3 marks]
Total for this question: 3
- Q6ORIGINALA hydrogen fuel-cell vehicle produces only water at the point of use. Explain why this does not prove that using the vehicle has no environmental impact.
[3 marks]
Total for this question: 3
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Printable question pack — 4.5 Energy changesAll 53 questions across 5 specification points — 47 more than the 6 above — with the full mark scheme. Guest accessible · browser print.Real past-paper questions
29 questions shown as printed, 10 reference-only · newest series first
Question and mark-scheme extracts © AQA. Reproduced for educational use; the original paper is linked on every question. Contact hello@oscarsongtutoring.co.uk for removal.
AQA 8462 · June 2025 · Paper 1F · Q2 · 6 marks
6 marks
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[02.6] Fewer than half of responses gave the correct answer, with more than half believing that temperature decreases in an exothermic reaction.
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Metals react with acids to produce a salt and a gas. A student investigated the temperature change when 1 g of each of several metals was added to 25 cm<sup>3</sup> of hydrochloric acid initially at 20 °C.
AQA 8462 · June 2025 · Paper 1F · Q3 · 8 marks
8 marks
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[03.1] Two thirds of students were able to identify sodium chloride solution as the only possible electrolyte. Water was the more popular distractor, but a surprising number chose solid potassium bromide.
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Cells contain chemicals that react to produce electricity. A cell used one fixed copper electrode and one metal electrode, both in an electrolyte. The measured voltages were: A 1.1 V, B 0.0 V, C 0.8 V, D 2.7 V.
AQA 8462 · June 2025 · Paper 1H · Q7 · 9 marks
9 marks
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[07.1] Whilst the majority of students reached level 1, only one in eight gave sufficient linked reasons to reach level 2. This was a high demand extended response question with the command word ‘evaluate’. Merely making comparisons from the information in the table was insufficient to gain credit. Consequences of those comparisons were necessary to count as linked reasons. An overall judgement or several individual judgements were necessary to reach Level 2, but many answers contained no judgement at all. Many students were able to link the states at room temperature to a consequence such as hydrazine being easier to store or transport. Many were also able to link the need for © 2025 AQA a catalyst to potential extra costs. However, they had difficulty with consequences of the other information in the table. Most students do not realise that when comparing data in an AO3 question, sometimes there is no real advantage of one option over the other and that is a valid point to make. Many tried to justify why being explosive was more dangerous than being toxic or vice versa, instead of simply deducing that both were dangerous in different ways. A large proportion of students seem to think that nitrogen is harmful in some way, rather than deducing that neither fuel cell produces harmful products. Few students deduced that the larger voltage from hydrazine means that fewer fuel cells would need to be used in a battery; instead, they merely stated that more power would be produced from a single hydrazine fuel cell. Some students tried to refer to atom economy, which is not relevant in this context as there is no ‘desired product’.
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Hydrazine, N<sub>2</sub>H<sub>4</sub>, is being researched for fuel cells. Hydrogen is a gas, explosive, gives 1.23 V and needs platinum; hydrazine is a toxic liquid, gives 1.61 V and needs no catalyst. Reactions: 2H<sub>2</sub> + O<sub>2</sub> -> 2H<sub>2</sub>O; N<sub>2</sub>H<sub>4</sub> + O<sub>2</sub> -> N<sub>2</sub> + 2H<sub>2</sub>O.
AQA 8462 · June 2024 · Paper 1F · Q3 · 9 marks
9 marks
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[03.8] Students struggled with this standard demand question, with only a quarter gaining a mark. More than a half of students selected the second distractor, in which both parts of the statement are the opposite of the correct version. When temperature decreases, heat energy is being taken in from the surroundings and converted to chemical energy, so the reaction is endothermic. It is this reduction in heat energy that causes the temperature decrease. A misconception for many students is thinking that when heat energy is taken in from the surroundings it remains as heat energy in the system, causing the confusion with the direction of temperature change.
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Zinc reacts with copper sulfate solution: zinc + copper sulfate -> zinc sulfate + copper. A student measured energy changes using 25 cm<sup>3</sup> of copper sulfate solution in a polystyrene cup and different masses of zinc powder.
AQA 8462 · June 2024 · Paper 1F · Q7 · 8 marks
8 marks
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[07.2] Two thirds of students identified sodium chloride solution as the correct substance to be an electrolyte. The two distractors, pure water and solid lead bromide, were equally popular.
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This question is about chemical cells. Figure 14 shows a cell with Metal A and Metal B in an electrolyte, with both metal electrodes connected to a voltmeter.
AQA 8462 · June 2024 · Paper 1H · Q4 · 8 marks
8 marks
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[04.2] This question discriminated well, with a quarter of students scoring 3 or 4 marks and the great majority scoring at least one mark. The question asked students to explain the results, but many simply described them. It was not sufficient just to describe the temperature increasing with the addition of more zinc; reference to the reaction being exothermic was also needed. The fact that the maximum temperature change occurred when 0.80 g of zinc was added was the mark scored most often, but many students were also able to explain this turning point in terms of no further reaction being possible because the zinc was now in excess. There were some excellent answers in terms of the zinc being the limiting reactant up to 0.8 g, after which the copper sulfate became the limiting reactant.
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A student investigated the energy change when different masses of zinc powder reacted with 25 cm<sup>3</sup> of copper sulfate solution in a polystyrene cup. A second student repeated the method four times using 0.50 g of zinc.
AQA 8462 · June 2024 · Paper 1H · Q6 · 11 marks
11 marks
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[06.1] Over three fifths of students scored all three marks. Most students could list the metals in order of decreasing reactivity, although some ignored the sign and ordered the metals in order of absolute magnitude of voltage. A few tried to remember the reactivity series, even though nickel and silver are not listed in the specification. The best answers justified the order not only in terms of the most reactive metal producing the most positive voltage, but also that the negative voltages were produced by elements less reactive than nickel.
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Figure 6 shows a chemical cell with a nickel electrode and electrode A in 1.0 mol/dm<sup>3</sup> sodium chloride, both connected to a voltmeter. Results for electrode A were: Cu -0.59 V; Mg 2.12 V; Ni 0.00 V; Ag -1.05 V; Zn 0.51 V.
AQA 8462 · June 2024 · Paper 1H · Q8 · 8 marks
8 marks
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[08.3] Over a quarter of students gained full marks on this high demand question, with half of students gaining at least 4 marks. Sometimes working was very difficult to follow; there was a page full of additions and subtractions with no words to explain what these represented. Just the words ‘broken’ and ‘made’ would have clarified the working enormously. The students who scored 4 marks had usually failed to recognise that the reaction is exothermic and therefore 2219 (the magnitude of the energy change) is given by (bonds made – bonds broken) since the energy for bonds made must be the larger value in an exothermic reaction. It should be noted that ΔH and its sign convention are not in the GCSE specification. Other common errors included: not including the C—C bonds: counting 3 C—C bonds instead of 2; complete omission of the value of the energy change.
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This question is about propane, C<sub>3</sub>H<sub>8</sub>. Figure 9 gives the displayed combustion equation: CH<sub>3</sub>-CH<sub>2</sub>-CH<sub>3</sub> + 5 O=O -> 3 O=C=O + 4 H-O-H. The overall energy released is 2219 kJ/mol. Bond energies: C-C 347, O=O 498, C=O in CO<sub>2</sub> 805, O-H 464 kJ/mol; C-H is X.
AQA 8462 · June 2023 · Paper 1F · Q10 · 6 marks
6 marks
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[10.5] This was very poorly answered. Only a handful of students scored both marks, with just over one in ten scoring one. Students are unfamiliar with the idea of uncertainty as the range about the mean, as stated in the specification. There were some good descriptions of the highest value being 0.3 °C above the mean and the lowest being 0.3 °C below the mean, but very few used the word uncertainty.
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A student dissolved different masses of ammonium nitrate in 200 cm<sup>3</sup> water and recorded the lowest temperature. For 8.0 g, four repeat temperatures were 16.2, 16.6, 16.8 and 16.4 °C, with mean 16.5 ± 0.3 °C.
AQA 8462 · June 2023 · Paper 1H · Q2 · 6 marks
6 marks
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[02.4] Nearly four fifths of students answered correctly in terms of the decrease of temperature. It was not necessary to refer to energy transfer as that is not shown in the results; however, those who did so usually referred correctly to energy being taken in. Those who contradicted their answer by giving an incorrect reference to energy being given out did not score the point.
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This question is about temperature changes. A student investigated the change in temperature of a solution when different masses of ammonium nitrate were dissolved in water. This is the method used. 1. Measure 200 cm<sup>3</sup> of water into a polystyrene cup. 2. Measure the temperature of the water. 3. Add 4.0 g of ammonium nitrate to the water. 4. Stir the solution until all the ammonium nitrate has dissolved. 5. Measure the lowest temperature reached by the solution. 6. Repeat steps 1 to 5 with different masses of ammonium nitrate. Table 2 shows the results (mass of ammonium nitrate added in grams / lowest temperature of solution in °C): 4.0 / 18.2; 8.0 / 16.2; 12.0 / 15.2; 16.0 / 13.6; 20.0 / 12.4; 24.0 / 10.6.
AQA 8462 · June 2023 · Paper 1H · Q4 · 7 marks
7 marks
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[04.4] Nearly three quarters of students scored both marks. Many fully correct diagrams were seen. The majority of students chose to use the format with a ring around each atom, but answer without rings were equally acceptable. A few students drew an extra electron on either hydrogen or carbon, and some drew ions instead of a molecule.
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This question is about hydrogen and compounds of hydrogen. Figure 3 shows the displayed formulae for the reaction between hydrogen and chlorine: H–H + Cl–Cl → 2 H–Cl. Table 4 shows the bond energies: H–H, 436 kJ/mol; Cl–Cl, 346 kJ/mol; H–Cl, 432 kJ/mol.
AQA 8462 · June 2022 · Paper 1F · Q10 · 6 marks
6 marks
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[10.5] This was poorly answered, with many students appearing to think the vertical axis involved temperature and/or time. Of those who did mention energy, many gave activation energy as one, or even both, of the answers. Only a quarter of students scored one mark and less than 10% scored both.
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Sodium carbonate reacts exothermically with hydrochloric acid: Na<sub>2</sub>CO<sub>3</sub>(s)+2HCl(aq) -> 2NaCl(aq)+CO<sub>2</sub>(g)+H<sub>2</sub>O(l). A student investigates how sodium-carbonate mass affects the highest temperature reached.
AQA 8462 · June 2022 · Paper 1H · Q2 · 6 marks
6 marks
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[02.2] Most students determined the gradient correctly, with many using the coordinates of the points at the limits of the printed line. Some appeared to misread the scale on the y-axis, reading 28.6 as 28.3 and 22.2 as 22.1. Many did not annotate their graph; those who read their coordinates incorrectly made it very difficult for examiners to judge whether the x-coordinates corresponded to the given y-coordinates. Students should always show their working in full, including annotating the graph. Units were usually given correctly, but g/°C was often seen. C° is not a correct representation of degrees Celsius.
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Sodium carbonate reacts exothermically with hydrochloric acid: Na<sub>2</sub>CO<sub>3</sub>(s)+2HCl(aq) -> 2NaCl(aq)+CO<sub>2</sub>(g)+H<sub>2</sub>O(l). A student investigates how sodium-carbonate mass affects the highest temperature reached.
AQA 8462 · November 2021 · Paper 1F · Q2 · 8 marks
8 marks
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Three batteries can power a TV remote. Zinc-carbon costs GBP0.17, is not rechargeable and lasts 5 months; alkaline costs GBP0.50, is not rechargeable and lasts 12 months; nickel-metal hydride costs GBP1.50, is rechargeable and lasts 8 months before recharge.
AQA 8462 · November 2021 · Paper 1F · Q4 · 9 marks
9 marks
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A student reacted cobalt, magnesium and zinc powders with 50 cm3 hydrochloric acid. Temperature increases (degC) were cobalt 6,7,5,9; magnesium 54,50,37,55; zinc 18,16,18,20. The anomalous magnesium result is 37.
AQA 8462 · November 2021 · Paper 1H · Q6 · 8 marks
8 marks
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[06.3] Students were expected to do a simple comparison of the temperature change when each metal was added separately to silver nitrate solution. A control variable was needed for full marks to be awarded, as well as how the results would show which metal was the more reactive. Some students did not appear to know how to progress, with some trying to measure a temperature change while heating with a Bunsen burner, and some appearing to confuse reactivity with melting or boiling point. Of those students who did realise what was required, many spoiled their control variable by referring to the same ‘amount’ of a substance instead of volume, or concentration, or mass, as appropriate to the substance. Many students referred to temperature rather than temperature change. A few students tried to get round the fact that no other chemicals were available by making zinc nitrate and then seeing if Q would react with it. This approach could have worked but only if they had taken steps to ensure that all the silver nitrate had reacted before adding Q.
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Substances A-D have: A mp -117 degC, bp 79 degC, non-conductor solid/liquid; B 801/1413, non-conductor solid, conductor liquid; C 1535/2750, conductor solid/liquid; D 1610/2230, non-conductor solid/liquid. Metal Q and zinc are both more reactive than silver.
AQA 8462 · November 2021 · Paper 1H · Q7 · 16 marks
16 marks
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[07.2] Many students were unable to write the formula of bromine. Those who could, often scored at least one mark, although the half-equation was not always balanced.
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This question compares electrolysis with chemical cells and investigates copper nitrate electrolysis. At 20 minutes, Figure 5 shows 0.12 g copper at 0.3 A and 0.24 g at 0.6 A.
AQA 8462 · November 2021 · Paper 1H · Q8 · 7 marks
7 marks
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[08.4] A good number of students were successful with this calculation, although some failed to count all of the bonds correctly. Where students made a slip of this nature, or an arithmetic error, it was sometimes impossible to award marks for following through with the method, since there was often a jumble of numbers scattered over the page with no words to explain what was going on. ‘Bonds broken’ and ‘bonds made’ should be stated in calculations of this type. Many students did not use the value of 1034 kJ/mol provided.
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2H<sub>2</sub>S(g)+3O<sub>2</sub>(g) -> 2H<sub>2</sub>O(g)+2SO<sub>2</sub>(g). Bond energies: H-S 364, O=O 498, O-H 464 kJ/mol; S=O is X. Energy released forming bonds is 1034 kJ/mol greater than energy needed to break bonds. The displayed equation contains four H-S and three O=O bonds broken, and four O-H and four S=O bonds formed.
AQA 8462 · November 2020 · Paper 1F · Q6 · 3 marks
3 marks
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A student adds citric acid to sodium hydrogencarbonate solution in 0.25 g steps and measures temperature. At 0.00, 0.25, 0.50, 0.75, 1.00 and 1.25 g, temperatures are 22.6, 22.2, 21.8, 21.4, 21.0 and 20.6 degC.
AQA 8462 · June 2019 · Paper 1F · Q2 · 4 marks
4 marks
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[02.6] Approximately 80% of students identified the reaction as exothermic, having been given a description.
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This question is about hydrogen peroxide, its catalysed decomposition and the formation of water.
AQA 8462 · June 2019 · Paper 1F · Q4 · 10 marks
10 marks
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[04.5] Over 90% of students identified an electric toy as the most suitable use for a non- rechargeable cell.
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A cell uses copper as one electrode and electrode X as cobalt, magnesium or zinc. Voltages are cobalt 0.62 V, magnesium 2.71 V, zinc 1.10 V.
AQA 8462 · June 2019 · Paper 1F · Q7 · 5 marks
5 marks
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[07.3] Approximately 50% of students identified the correct type of error represented by the loss of energy.
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A student investigates neutralisation temperature using potassium hydroxide and additions of dilute sulfuric acid.
AQA 8462 · June 2019 · Paper 1H · Q5 · 10 marks
10 marks
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[05.2] Only a small proportion of students were able to give a limitation of a dot and cross diagram. The most common correct response was that the molecule was not shown in 3 dimensions. Common responses seen that were not credited included: • only shows the outer electrons • does not show the structure • does not show the intermolecular forces.
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Ammonia is a small covalent molecule. It reacts by 4NH3+3O2->2N2+6H2O. Bond energies kJ/mol: N-H 391, O=O 498, N≡N 945, O-H 464.
AQA 8462 · June 2019 · Paper 1H · Q6 · 9 marks
9 marks
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[06.2] Most students scored the 2 marks for the order of reactivity of the top four metals and the justification for this order. The most common error was then to put silver above copper in the order of reactivity. However, only a small proportion of students were able to explain the negative voltage for silver in terms of its reactivity compared with copper.
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A cell uses copper as one electrode. Electrode X voltages: cobalt +0.62 V, copper 0.00, magnesium +2.71, nickel +0.59, silver -0.46, tin +0.48.
AQA 8462 · June 2019 · Paper 1H · Q9 · 8 marks
8 marks
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[09.1] Almost a half of students scored 0 marks. The mark scheme required the use of comparatives. Common correct responses were: • Better insulator • Less heat loss Common responses seen that were not credited included: • good insulator • no heat loss.
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Sulfuric acid is added to 25.0 cm3 KOH in a polystyrene cup. A later run uses 15.5 cm3 of 0.500 mol/dm3 H2SO4. Equation: 2KOH+H2SO4->K2SO4+2H2O.
AQA 8462 · June 2018 · Paper 1F · Q10 · 5 marks
5 marks
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[10.4] 25% of students achieved both marks. Many realised that the missing reactant was oxygen, but were unable to write its formula correctly so lost both marks. A few achieved a single mark for writing the correct formula for oxygen without correctly balancing the equation.
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A simple cell uses copper and zinc in sodium chloride solution. This question compares alkaline batteries, hydrogen fuel cells and lithium-ion vehicle batteries.
AQA 8462 · June 2018 · Paper 1H · Q3 · 5 marks
5 marks
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[03.2] 62% of students answered this question on a new area of the specification correctly. Many, however, mixed up the answers to questions 03.2 and 03.3. Many thought that charge, energy, or a product run out.
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A simple cell uses copper and zinc in sodium chloride solution. This question compares alkaline batteries, hydrogen fuel cells and lithium-ion vehicle batteries.
AQA 8462 · June 2018 · Paper 1H · Q7 · 11 marks
11 marks
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[07.2] Although this historically is a well-known area of the specification, lack of precision in answers cost some students greatly. 16% of students achieved all three marks, with 72% gaining some credit. The electrons are not (all) closer to the nucleus in chlorine – the outer electrons are. The relevant force of attraction is between the outer electrons and the nucleus, and is not intermolecular, magnetic or gravitational. Attracting another electron is not the same as gaining it.
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This question concerns chlorine, iodine, hydrogen chloride and sunlight substitution of methane by bromine. Bond energies give reaction change -51 kJ/mol.
AQA 8462 · sample1 · Paper 1H · Q9 · 11 marks
11 marks
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Ethene reacts with bromine with overall energy change -95 kJ/mol. Bond energies include C=C 612, C-C 348, C-H 412 and C-Br 276 kJ/mol.
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November 20206 questions
- Paper 1F · Q3Foundation · 8 marks · multi · standardView question in paper (p.10)
- Paper 1F · Q9Foundation · 11 marks · multi · standardView question in paper (p.32)
- Paper 1H · Q2Higher · 11 marks · multi · standardView question in paper (p.4)
- Paper 1H · Q6Higher · 9 marks · multi · standardView question in paper (p.16)
- Paper 1H · Q7Higher · 10 marks · multi · standardView question in paper (p.18)
- Paper 1H · Q9Higher · 11 marks · multi · standardView question in paper (p.26)
June 20182 questions
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