What is a dynamic equilibrium?

Consider the reversible reaction: A + B to C + D

Let’s say you start with only the reactants A and B, at first they will react together to from some of C and D. This is called the forward reaction.

As the forward reaction begins you start to generate some C and D. They can then react together to form A and B. This is called the backward reaction (as you’re going back to the reactants).

Initially your reaction will have a higher rate of forward reaction to backward reaction, (as you lots of A and B to react with each other but only a little bit C and D that can react with each other).

As you generate more C + D and have less A + B available to react, the rate of forward reaction starts to decrease and the rate of backward reaction starts to increase.

Eventually you will reach a point where the forward reaction and the backward reaction have the same rate, at this point you will have reached a dynamic equilibrium. So the amounts of A, B, C and D all stay the same but both the forward and backward reactions are still taking place! Remember a dynamic equilibrium does not have to be a 50:50 split between reactants and products only the rates of forward and back reaction are the same!