An Approximation Leading To The Binomial Distribution In The Stochastic Treatment Of A Reversible Chemical Reaction

Abstract

The exact equilibrium distribution of the number of molecules of C in the reversible chemical reaction A+B ^=S: C is shown to converge to the binomial distribution when N is finite, M—»!K, K—>0 in such a way that KM is finite, where M, N and K are respectively, the total number of molecules of A, the total number of molecules B and the ratio of the forward to the backward reaction rates, Ki/Kz. The practical implication of this limiting condition have been investigated by numerically computing the two distributions for a wide range of values of the parameters. Under the same conditions, the transient distribution of C(t), the number of C molecules at time t, is shown to be approximately a convolution of two binomial distributions.