Question

Explain the following: 

An increase of 10 K in temperature rarely doubles the kinetic energy of particles but this increase in temperature may be enough to double the rate of reaction.

Answer 1

1. The average kinetic energy of particles is directly proportional to the absolute temperature T:
   Average K.E. ∝ T
2. An increase of 10 K causes only a small percentage increase in average kinetic energy, not enough to double it.
3. The rate of reaction depends on the fraction of molecules having energy equal to or greater than the activation energy (E_a​).
4. According to the Arrhenius equation \[\ce{k = Ae^{−Ea/(RT)}}\] a small increase in T causes a large exponential increase in this fraction.
5. More molecules with E ≥ E_a means more effective collisions per unit time.
6. As a result, even a 10 K rise in temperature can double the reaction rate while only slightly increasing average kinetic energy.