Why does increasing temperature increase the rate of reaction?

Increasing temperature increases the rate of reaction for 2 reasons: the first (minor) reason is that particles have more kinetic energy with increasing temperature, so there are more collisions between reactant particles the second reason is that at higher temperature, more particles have more energy, thus more of the particles have energy greater than (or equal to) the activation energy, so more collisions will result in a reaction per unit time.