Difference between instantaneous rate of a reaction and average rate of a reaction.

Average rate of a reaction Instantaneous rate

The rate of change of concentration of species for a finite interval of time. Instantaneous rate is the rate of a reaction at a specified or particular point of time.

It is meant for a time interval. Instantaneous rate is for a point of time in a reaction when dt →0.

It is given by,

Ravg= -1/a(Δ[R]/Δt) = 1/b(Δ[R]/Δt It is given by,

Rinst = -d[R]/dt = +d[P]/dt

At a point dt →0.