A student monitors a reaction in which a purple solution gradually loses its colour. The colour intensity of the mixture is recorded at regular intervals.
| Time in s | 0 | 20 | 40 | 60 | 80 | 100 | 120 |
|---|---|---|---|---|---|---|---|
| Colour intensity in arbitrary units | 92 | 61 | 38 | 20 | 9 | 4 | 4 |
Use the readings to state the earliest recorded time after which no further measurable change occurred. Give evidence for your choice.
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.