A student tests three solids as catalysts for the decomposition of hydrogen peroxide.
The student adds 0.50 g of each solid to the same volume of hydrogen peroxide solution and times how long it takes to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen. The student then dries and weighs the solid.
| Solid added | Mass at end (g) | Time to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen (s) |
|---|---|---|
| none | – | more than 600 |
| manganese(IV) oxide | 0.50 | 25 |
| copper(II) oxide | 0.50 | 110 |
| solid X | 0.21 | 40 |
Which conclusion is correct?
Solid X is a better catalyst than copper(II) oxide, because it gives oxygen faster.
Manganese(IV) oxide is the best catalyst. Solid X is not a catalyst, because it is used up.
Copper(II) oxide is not a catalyst, because it gives oxygen more slowly than solid X.
All three solids are catalysts, because they all speed up the reaction.
60 exam-style questions on OCR GCSE Chemistry 4.1 Predicting chemical reactions, covering 4.1.1 Properties and trends in Groups 1, 7 and 0, 4.1.2 Properties of the transition metals, 4.1.3 Reactivity predicted from position in the Periodic Table, and 4.1.4 Reactivity of metals and the reactivity series. Each one has a worked solution and a mark scheme showing where the marks go.