A student reacts a piece of magnesium ribbon with excess dilute sulfuric acid.
The student collects the hydrogen gas in a gas syringe and records the volume every 10 seconds.
The table shows the results.
| Time (s) | Volume of hydrogen (cm3\mathrm{cm^{3}}cm3) |
|---|---|
| 0 | 0 |
| 10 | 14 |
| 20 | 26 |
| 30 | 36 |
| 40 | 43 |
| 50 | 48 |
| 60 | 50 |
| 70 | 50 |
| 80 | 50 |
Name one other piece of apparatus that could be used to measure the volume of hydrogen.
Calculate the mean rate of reaction in the first 20 seconds.
Use the equation: mean rate of reaction = volume of gas ÷ time
Give the unit.
Describe how the rate of reaction changes from 0 to 80 seconds. Use the results.
Explain why the volume of hydrogen stops increasing after 60 seconds.
Suggest a different measurement the student could make to follow the rate of this reaction.
Another student suggests measuring the loss in mass of the flask on a balance.
Explain why this method is not suitable for this reaction.
56 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.