Parallel and Sequential Reactions


 

Parallel or Competing Reaction 

The reactions in which a substance reacts or decomposes in more than one way are called parallel or side reactions.

 

If we assume that both  of them are first order, we get.

k1 = fractional yield of B × kav

k2 = fractional yield of C × kav

If k1 >  k2 then

A → B main and

 

A → C is side reaction

Let after a definite interval x mol/litre of B and y mol/litre of C are formed.

i.e

This means that irrespective of how much time is elapsed, the ratio of concentration of B to that  of C from the start (assuming no B  and C in the beginning ) is a constant equal to k1/k2.

Refer to the following video for parallel reactions:

 

Example of Parallel Reactions