For many reactions a 10°C rise in temperature doubles the reaction rate. Why are most reactions very sensitive to changes in temperature, making increasing temperature a very effective way in increasing reaction rate?

At lower temperatures only a small fraction of the particles have very low or very high Ek and the majority have E close to the average Ek. At lower temps, the proportion of particles that have energy equal or greater than the Ea is shown by the small blue shaded area If temperature is increased, then the fraction of particles with low Ek decreases, fraction with high Ek increase. At this temp, proportion of particles that have energy =< Ea is shown by both shaded areas. This shows that there is a large increase in the proportion of particles that have enough energy to form an activated complex.