The mass of a solid reactant remaining during a reaction is plotted against time. At 45 s, the tangent to the curve passes through (20 s,8.4 g)(20\ \text{s}, 8.4\ \text{g})(20 s,8.4 g) and (70 s,5.9 g)(70\ \text{s}, 5.9\ \text{g})(70 s,5.9 g).
What is the rate at which the solid reactant is used up at 45 s?
0.050 g/s0.050\ \text{g/s}0.050 g/s
0.42 g/s0.42\ \text{g/s}0.42 g/s
0.036 g/s0.036\ \text{g/s}0.036 g/s
0.084 g/s0.084\ \text{g/s}0.084 g/s
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.