Iron is added during the formation of ammonia. The same starting mass of iron is used in each test, and the time taken to form a fixed amount of ammonia is measured.
| Result | Time compared with no iron | Mass of iron at the end compared with the start |
|---|---|---|
| A | longer | lower |
| B | shorter | lower |
| C | longer | the same |
| D | shorter | the same |
Which result would show that the iron had acted as a catalyst?
Result D
Result A
Result B
Result C
122 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.