Collision Theory and Reaction Rate

In an endothermic process, the activation energy for the forward reaction is much greater than the activation energy for the reverse reaction. Heating the system increases the forward rate at which reactants are turned into products. The equilibrium shifts to the right as more products form.

In an exothermic process, the activation energy for the reverse reaction is much greater than for the forward reaction. If the system is heated the rate of the reverse reaction increases and more reactants form. The equilibrium shifts to the left.

The rate of reaction is dependent on the frequency of collision between reacting particles. The greater concentration of the reacting particles, the greater the collision frequency. Over time the reacting particles are consumed and their concentration decreases.

Equilibrium is achieved when the rate of the forward reaction equals the rate of the reverse reaction.