A student investigates how the concentration of sodium thiosulfate solution affects the time for a cross to disappear. All other conditions are kept the same.
| Concentration in g dm−3\mathrm{g\,dm^{-3}}gdm−3 | Time for cross to disappear in s |
|---|---|
| 10 | 80 |
| 20 | 40 |
| 30 | 27 |
| 40 | 20 |
Which conclusion is supported by these results?
The time is directly proportional to the concentration
The rate doubles for every 10 g dm−310\,\mathrm{g\,dm^{-3}}10gdm−3 increase in concentration
The rate is directly proportional to the concentration
The rate is inversely proportional to the concentration
127 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.