An aqueous reaction produces a gas. A student investigates the effect of adding solids P, Q and R to the reaction.
The student measures the time taken to collect 40 cm3 of gas. At the end of each test, the student filters off the solid, washes it, dries it and measures its mass. All other conditions are kept the same.
| Solid added | Time taken to collect 40 cm3 of gas in s | Mass of solid added in g | Mass of dry solid recovered in g |
|---|---|---|---|
| none | 96 | — | — |
| P | 34 | 0.60 | 0.60 |
| Q | 29 | 0.60 | 0.42 |
| R | 96 | 0.60 | 0.60 |
Evaluate the results and identify which, if any, of P, Q and R is a catalyst for this reaction.
122 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.