Exam Style Question - 1

Question: Use the Maxwell-Boltzmann distribution to explain why a small increase in temperature causes a large increase in the rate of a reaction. (3 marks)At a higher temperature the molecules have more kinetic energy on average. The distribution curve moves to the right: the peak becomes lower and shifts to a higher energy. The area under the curve stays the same, because the total number of molecules has not changed.Mark 1: a much larger proportion of molecules now have energy greater than or equal to the activation energy. This is shown by the larger area under the curve to the right of E_a.Mark 2: so there are many more collisions with enough energy to react.Mark 3: this means more successful collisions per unit time, so the rate increases. The molecules also collide more often, but this is a much smaller effect.Answers that only say that particles move faster or collide more often do not score full marks. The key idea is the proportion of molecules with energy at or above the activation energy.