A student adds 1.00 g of different solids to separate samples of hydrogen peroxide solution. Each solid is recovered, dried and weighed at the end.
| Solid added | Time to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen in s | Mass of solid recovered in g |
|---|---|---|
| no solid added | more than 600 | not applicable |
| copper(II) oxide | 95 | 1.00 |
| manganese(IV) oxide | 28 | 0.99 |
| zinc oxide | 420 | 1.00 |
| substance X | 40 | 0.62 |
Which conclusion is best supported by the results?
Substance X is a catalyst, because it greatly increases the rate of the reaction
Zinc oxide is not a catalyst, because it increases the rate by only a small amount
Copper(II) oxide is the best catalyst, because none of its mass is lost at all
Manganese(IV) oxide is the best catalyst; its small mass change is a recovery loss
54 exam-style questions on Edexcel GCSE Chemistry 8.1 Rates of reaction, covering 8.1.1 Measuring and interpreting rates of reaction, 8.1.2 Collision theory and the factors affecting rate, and 8.1.3 Catalysts and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.