A student reacts marble chips with dilute hydrochloric acid in a conical flask with a cotton wool plug in the neck. Carbon dioxide escapes through the cotton wool. The student places the flask on a balance and records its mass at regular intervals.
| Time (s) | Mass of flask and contents (g) |
|---|---|
| 0 | 150.00 |
| 30 | 149.32 |
| 60 | 148.91 |
| 90 | 148.71 |
| 120 | 148.66 |
| 150 | 148.66 |
Describe the pattern in the rate of reaction during the 150 seconds. Support your answer with values from the table.
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.