A student compares how fast magnesium ribbon and magnesium powder react with dilute hydrochloric acid. She uses the same mass of magnesium and the same volume and concentration of acid each time. She measures the volume of hydrogen gas produced in the first 20 seconds.
The table shows her results.
| Form of magnesium | Volume of hydrogen in the first 20 s in cm3\mathrm{cm^{3}}cm3 |
|---|---|
| ribbon | 18 |
| powder | 50 |
Use the equation: mean rate of reaction=volume of gastime\displaystyle \text{mean rate of reaction} = \frac{\text{volume of gas}}{\text{time}}mean rate of reaction=timevolume of gas
Calculate the mean rate of reaction for the magnesium powder in the first 20 s. Give the unit.
Explain, in terms of particles, why the magnesium powder reacts faster than the magnesium ribbon.
Both experiments produced the same total volume of hydrogen by the end. Suggest why.
The student repeats the experiment with magnesium ribbon and more concentrated acid. Explain why the rate of reaction increases.
Some reactions take place between gases. State the effect of increasing the pressure on the rate of a reaction between gases.
54 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.