Oxford Revise AQA GCSE Combined Science Foundation | Chapter C8 answers

C8: Energy changes

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

exothermic

increase

endothermic

decrease

conserved

four marks for all correct

three marks for three correct

two marks for two correct

one mark for one correct

4

AO1

5.5.1.1

01.2

combustion

1

AO1

5.5.1.1

01.3

self-heating can/hand warmer/burning fuels/respiration

accept any reasonable answer

1

AO1

5.5.1.1

02.1

thermometer/data logger/temperature probe

1

AO2

5.5.1.1

02.2

wear goggles/wash hands

AO3

5.5.1.1

02.3

26.5 – 25.0 = 1.5

°C

1

1

AO1

5.5.1.1

02.4

Plot point at (60, 26.2)

1

AO2

5.5.1.1

02.5

exothermic

temperature increased/heat energy released

1

1

AO2

AO3

5.5.1.2

03.1

pack B – cold

pack A – hot

1

AO2

5.5.1.1

03.2

35 minutes

1

AO2

5.5.1.1

03.3

pack A

1

AO2

5.5.1.1

03.4

endothermic

1

AO2

5.5.1.1

03.5

Level 3: At least one advantage and disadvantage provided of both new temperature pack and hot water bottle. Justified conclusion given on whether club should switch or not.

5-6

AO3

5.5.1.1

Level 2: Advantages and disadvantages for new packs and hot water bottle provided, but an advantage OR disadvantage missing for one. A conclusion on whether the club should switch given, but justification is simple or not clear.

3-4

Level 1: Conclusion given but no justification. Attempt at evaluating the pack against a hot water bottle, but advantages and disadvantages have not been provided for one OR an advantage/disadvantage missing from both.

1-2

No relevant content.

0

Indicative content:

new pack – advantages

  • quick (no preparation)
  • can carry them around with you
  • instant relief

new pack – disadvantages

  • can only be used once
  • goes to landfill or not recycled
  • no temperature regulation

hot water bottle – advantages

  • reusable
  • minimal cost/don’t need to buy packs/only cost in electricity of boiling/freezing water

how water bottle – disadvantages

  • takes time to produce
  • cannot control temperature
  • needs a supply of hot water

04.1

endothermic

exothermic

exothermic

endothermic

1

1

1

1

AO1

5.5.1.1

04.2

it transfers energy to the surroundings

1

AO1

5.5.1.1

04.3

exothermic

1

AO2

5.5.1.1

05.1

insulated container/cup (with lid)

reduce energy transfers/heat loss to the surroundings

1

1

AO3

5.5.1.1

05.2

stir

to ensure that the solution is the same temperature throughout or to make it dissolve faster

1

1

AO3

5.5.1.1

05.3

D

1

AO3

5.5.1.1

05.4

temperature change would be less

1

AO3

5.1.1.1

06.1

temperature change

1

AO2

5.5.1.1

06.2

two from:

  • concentration of acid
  • volume of acid
  • mass of metal

one mark for each correct answer up to two marks

accept other suitable answers

2

AO2

5.5.1.1

06.3

copper does not react with dilute hydrochloric acid/is unreactive

1

AO2

5.4.1.2

06.4

magnesium 17.7

zinc 6.1

both values required for the mark

1

AO1

5.5.1.2

06.5

magnesium

greatest temperature increase/is the most reactive

1

1

AO2

5.1.1.1

07.1

B and C

1

AO2

5.1.1.2

07.2

B

1

AO2

5.1.1.2

07.3

C

1

AO2

5.1.1.2

08.1

iron oxide

1

AO2

5.1.1.1

08.2

oxidation

iron gains oxygen/loses electrons

1

1

AO1

5.4.1.1

08.3

collide

activation energy

1

1

08.4

exothermic

1

08.5

products below reactants

curved line starting at reactants, going up, then coming down to products

allow error carried over from question 08.4

1

1

09.1

data logger

fewer mistakes will be made in reading data/it takes more readings

1

1

AO3

5.5.1.1

09.2

\(
\begin{align}
& \frac{32.6 + 32.9 + 32.5}{3} = \frac{98}{3} = 32.66… \\
& = 32.7
\end{align}
\)

1

1

AO2

5.5.1.1

09.3

second student

allow time for reaction to occur

1

1

AO3

5.5.1.2

09.4

reacting particles at low temperature

so most did not have sufficient energy/energy above the activation energy when they collided

and so most collisions did not cause a reaction

1

1

1

AO2

5.5.1.2

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