A portable heater uses a solid reactant that reacts with a solution. The manufacturer wants the reaction to continue for longer, so supplies the solid as one large tablet rather than as the same mass of small granules. The solution and temperature are the same in each case. Why does using one large tablet slow down the reaction?
A smaller area of solid is exposed, so collisions with solution particles happen less often
The tablet lowers the concentration of the solution, so solution particles collide less often
The particles that make up the tablet are larger, so they collide less often with the solution
Particles inside the tablet have less kinetic energy, so their collisions are less successful
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.