# Question #b54e2

Jul 17, 2015

${K}_{c} = \frac{{\left[H I\right]}^{2}}{\left[{H}_{2}\right] \left[{I}_{2}\right]}$

Where [ ] represents concentrations at equilibrium.

#### Explanation:

In general for a reaction:

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

• the expression for ${K}_{c}$ is given by:

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

Where [ ] represents concentration of the species at equilibrium.

If we apply the general rule to this specific reaction:

${H}_{2 \left(g\right)} + {I}_{2 \left(g\right)} r i g h t \le f t h a r p \infty n s 2 H {I}_{\left(g\right)}$

we get:

${K}_{c} = \frac{{\left[H I\right]}^{2}}{\left[{H}_{2}\right] \left[{I}_{2}\right]}$

Note that whenever you quote a value for ${K}_{c}$ you must also state the temperature as well.