Hydrogen peroxide decomposes to make water and oxygen. A student adds 1.00 g of different powders to separate samples of the same hydrogen peroxide solution. The student times how long it takes to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen. At the end, the student filters, dries and weighs each powder.
| Powder | Mass at start (g) | Mass at end (g) | Time to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen (s) |
|---|---|---|---|
| none | 0.00 | 0.00 | 300 |
| W | 1.00 | 1.00 | 300 |
| X | 1.00 | 0.64 | 20 |
| Y | 1.00 | 1.00 | 90 |
| Z | 1.00 | 1.00 | 45 |
Which powder is the most effective catalyst for this reaction?
Powder W
Powder X
Powder Y
Powder Z
56 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.