A mixture turns cloudy as an insoluble solid forms. When one dissolved reactant has a concentration of 0.30 mol/dm3, a cross drawn under the flask is hidden after 120 s. For this reaction, the rate and the concentration of that reactant are directly proportional. Which concentration of the reactant would hide the cross after 80 s?
0.45 mol/dm30.45\ \text{mol/dm}^30.45 mol/dm3
0.90 mol/dm30.90\ \text{mol/dm}^30.90 mol/dm3
0.40 mol/dm30.40\ \text{mol/dm}^30.40 mol/dm3
0.20 mol/dm30.20\ \text{mol/dm}^30.20 mol/dm3
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.