A fire-safety scientist investigated the rate at which a solid fuel burned in oxygen.
The solid fuel was prepared with three different particle sizes. Each trial used 5.0 g of fuel. The temperature and the method used to ignite the fuel were the same in all three trials. Oxygen was in excess.
The table shows the results.
| Trial | Total exposed surface area of fuel in cm2\text{cm}^2cm2 | Initial oxygen pressure in kPa\text{kPa}kPa | Mass of fuel that reacted in the first 20 s in g\text{g}g |
|---|---|---|---|
| A | 80 | 100 | 0.60 |
| B | 320 | 100 | 1.80 |
| C | 900 | 150 | 3.60 |
Calculate the mean rate at which the fuel reacted in trial B during the first 20 s.
Give the unit.
Explain why the results from trials A and B support the conclusion that increasing the surface area of a solid increases the rate of reaction.
The scientist stated that trial C provided further evidence that increasing the surface area increased the rate of reaction.
Evaluate this statement.
127 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1a Calculating rates of reactions, 6.1.1b Gradient of a tangent as rate, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.