# A student adds manganese(IV) oxide powder to a solution of hydrogen peroxide. The student observes that gas is produced rapidly, but at the end of the reaction the mass of manganese(IV) oxide is unchanged. Explain the role of the manganese(IV) oxide in this reaction and explain, in terms of particles, why using a larger mass of manganese(IV) oxide powder would increase the rate of gas production.

> Eduqas GCSE Chemistry — C6 Rate and extent of chemical change · Explain · 4 marks

## Mark scheme (4 marks)

1. Manganese(IV) oxide acts as a catalyst
2. A catalyst speeds up the rate of reaction without being used up / without changing in mass or chemical composition
3. A larger mass of manganese(IV) oxide provides a greater surface area (more active sites / more surface exposed to hydrogen peroxide particles)
4. More frequent collisions between hydrogen peroxide particles and the catalyst surface, so more successful collisions per second / reaction happens faster

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