# How is the value of the equilibrium constant useful?

Nov 26, 2014

The value of the equilibrium constant tells us the extent to which the reactants or products predominate in a system which is at equilibrium.

Consider a general case :

$a A + b B r i g h t \le f t h a r p \infty n s c C + \mathrm{dD}$

The expression for the equilibrium constant in terms of concentration is:

${K}_{c} = \frac{{\left[C\right]}^{c} {\left[D\right]}^{d}}{{\left[A\right]}^{a} {\left[B\right]}^{b}}$

You can see that if the position of equilibrium lies to the right then $\left[C\right]$ and $\left[D\right]$ will be large and [A] and [B] will be small giving a large value of ${K}_{c}$.

$K$ only depends on temperature so this must always stated when quoting any values.