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CAIE IGCSE Chemistry 5. Chemical energetics Question Bank

Practise energy changes in reactions through temperature data, pathway diagrams, activation energy and bond-energy calculations.

Syllabus
2026–2028
Course
Chemistry 0620

Covered syllabus points

5.1 Exothermic and endothermic reactions

5. Chemical energetics question 1

[Maximum number: 1]

When an acid is added to an alkali, the temperature of the reaction mixture rises.
Which words describe this reaction?

A

decomposition and endothermic

B

decomposition and exothermic

C

neutralisation and endothermic

D

neutralisation and exothermic

5. Chemical energetics question 2

[Maximum number: 1]

Which row describes the changes that occur in an endothermic reaction?

energy change

temperature

energy given out to
the surroundings

decreases

energy given out to
the surroundings

increases

energy taken in from
the surroundings

decreases

energy taken in from
the surroundings

increases

5. Chemical energetics question 3

[Maximum number: 2]

Question (a)

(a)

The energy level diagram shows the energy profile for the reaction between zinc and dilute sulfuric acid.

Figure for Question (a) — CAIE IGCSE Chemistry
[ 2 ]

Question (i)

(i)

Draw an arrow on the diagram to represent the activation energy.

[ 1 ]

Question (ii)

(ii)

Is the reaction endothermic or exothermic? Explain your answer.

[ 1 ]

5. Chemical energetics question 4

[Maximum number: 2]

The Haber process is used to manufacture ammonia.

Question (a)

(a)

The equation for the Haber process is shown.

N2( g)+3H2( g)⇌2NH3( g)ΔH=−92 kJ/mol\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g}) \quad \Delta H=-92 \mathrm{~kJ} / \mathrm{mol}

The reaction is reversible. The forward reaction is exothermic.

[ 2 ]

Question (i)

(i)

State what is meant by the symbol ΔH\Delta H.

[ 1 ]

Question (ii)

(ii)

ΔH\Delta H for the forward reaction is −92 kJ/mol-92 \mathrm{~kJ} / \mathrm{mol}.

State why this value shows that the forward reaction is exothermic.

[ 1 ]
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