A student follows a reaction that gives off carbon dioxide. The flask has a cotton wool plug in its neck and is placed on a balance. The student records the mass at three times.
| Time (s) | 0 | 40 | 100 |
|---|---|---|---|
| Mass (g) | 150.00 | 149.40 | 148.95 |
Calculate the mean rate of mass loss from 0 s to 40 s and from 40 s to 100 s, in g/min.
Explain why the mean rate of mass loss from 40 s to 100 s is lower than from 0 s to 40 s. Use ideas about particles.
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.