Consider the complex reaction scheme in a semi-continuous reactor:

(desired reaction) and

(undesired reaction). The governing equations in their dimensionless form are:

where

for

and

for

,

is the Damköhler number,

is the reactor residence time,

is the dimensionless mixing time,

is the mixing time,

is dimensionless time,

is the dimensionless concentration of species

*, *is the initial concentration ratio,

is the degree of segregation,

and

are the rate constants of the two reactions, and

is the ratio of the two reaction rate constants. The initial conditions are:

, and

. We define the selectivity by

so that when

no desired product

is obtained. This Demonstration displays the selectivity

as a function of the dimensionless time

for various values of

,

,

, and

.