CAIE IGCSE Chemistry Rate of Reaction Question Bank

Practise measuring and interpreting reaction rates and explaining how concentration, pressure, surface area, temperature and catalysts change collision frequency.

Syllabus
2026–2028
Topic
6.2
Level
—

Exam points

  • calculate or compare rate from change in mass, gas volume or concentration over time
  • interpret curve gradient and plateau to compare initial rate, duration and final amount
  • explain rate changes through collision frequency, energy and activation energy

Covered syllabus points

6.2.1—Rate changes caused by concentration6.2.2—Catalyst increases the rate of a6.2.3—Practical methods for investigating6.2.4—Interpret data6.2.5—Collision theory in terms of: (a)6.2.6—Rate changes using collision theory6.2.7—Catalyst decreases the activation6.2.8—Evaluate practical methods for

6.2 Rate of reaction question 1

[Maximum number: 5]

Some elements are shown in the order they appear in the reactivity series. The most reactive element is at the top.
> sodium calcium magnesium aluminium zinc iron hydrogen copper

Question (a)

(a)

When zinc granules are added to aqueous copper(II) sulfate, a reaction occurs. During the reaction, a red-pink solid is formed and the solution becomes colourless.

[ 5 ]

Question (i)

(i)

Explain, in terms of particles, why the rate of this reaction increases when the temperature is increased.

[ 3 ]

Question (ii)

(ii)

Suggest two other ways of increasing the rate of this reaction.

1

2

[ 2 ]

6.2 Rate of reaction question 2

[Maximum number: 1]

Sulfuric acid can be manufactured from the raw materials sulfur, air and water. The process can be divided into four stages.
stage 1 converting sulfur into sulfur dioxide
stage 2 converting sulfur dioxide into sulfur trioxide
stage 3 converting sulfur trioxide into oleum, H2 S2O7\mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{7}
stage 4 converting oleum into sulfuric acid
stage 1

Sulfur dioxide is converted into sulfur trioxide according to the following equation.

2SO2+O2⇌2SO32 \mathrm{SO}_{2}+\mathrm{O}_{2} \rightleftharpoons 2 \mathrm{SO}_{3}

The reaction is carried out at a temperature of 450∘C450^{\circ} \mathrm{C} and a pressure of 1-2 atmospheres using a catalyst. The energy change, ΔH\Delta H, for the reaction is −196 kJ/mol-196 \mathrm{~kJ} / \mathrm{mol}.

Why is a catalyst used?

6.2 Rate of reaction question 3

[Maximum number: 8]

Hydrogen peroxide, H2O2\mathrm{H}_{2} \mathrm{O}_{2}, decomposes into water and oxygen in the presence of a catalyst, manganese(IV) oxide.

2H2O2(aq)→2H2O(l)+O2( g)2 \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq}) \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{O}_{2}(\mathrm{~g})

Question (a)

(a)

What is meant by the term catalyst?

[ 2 ]

Question (b)

(b)

A student studies the rate of decomposition of hydrogen peroxide using the apparatus shown. The student uses 20 cm320 \mathrm{~cm}^{3} of 0.1 mol/dm30.1 \mathrm{~mol} / \mathrm{dm}^{3} hydrogen peroxide and 1.0 g of manganese(IV) oxide.

The student measures the volume of oxygen given off at regular time intervals until the reaction stops. A graph of the results is shown.

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

Question (i)

(i)

When is the rate of reaction highest?

[ 1 ]

Question (ii)

(ii)

Suggest one method of increasing the rate of reaction using the same amounts of hydrogen peroxide and manganese(IV) oxide.

[ 1 ]

Question (c)

(c)

What would be the effect on the volume of oxygen produced if the mass of catalyst was increased?

[ 1 ]

Question (d)

(d)

The student carries out a second experiment to investigate whether another substance, copper(II) oxide, is a better catalyst than manganese(IV) oxide.

Describe how the second experiment is carried out. You should state clearly how you would make sure that the catalyst is the only variable.

[ 3 ]
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