The number of collisions of n1 molecules of A1, n2 molecules of A2 ... is accordingly proportional to C1n1C2n2 ..., and the reaction-velocity corresponding to it is therefore
v = kC1n1C2n2 ...,
and similarly the opposed reaction-velocity is
v′ = k′C′1n′1C′2n′2 ...;
the resultant reaction-velocity, being the difference of these two partial velocities, is therefore
V = v - v′ = kC1n1C2n2 ... - k′C′1n′1C′2n′2 ...
This is the most general expression of the law of chemical mass-action, for the case of homogeneous systems.
Equating V to zero, we obtain the equation for the equilibrium state, viz.
C1n1C2n2 ... / C′1n′1C′2n′2 ... = k / k′ = K;
K is called the “equilibrium-constant.”