For a chemical reaction H_2 + I_2 → 2HI, Find out the equilibrium constant at 426°C, if concentrations of H_2, I_2, HI are respectively 0.0037 mol/L, 0.0037 mol/L and 0.0276 mol/L at equilibrium (at 426°C).
Also, find the equilibrium constant for the reverse equation.
Given, [HI] = 0.0276 mol/L, [H_2] = 0.0037 mol/L and [I_2] = 0.0037 mol/L.
(a) Equilibrium constant from the mass action law is given by:
K= \frac{\left[HI\right]^2 }{\left[H_2\right]^1 \left[I_2\right]^1 } = \frac{0.0276^2}{0.0037 \times 0.0037} = 55.6
(b) For the reverse equation:
2HI \longrightarrow H_2 + I_2
K^\prime = \frac{\left[H_2\right]^1 \left[I_2\right]^1 }{\left[HI\right] } = \frac{0.0037 \times 0.0037}{0.0276^2} = \frac{1}{55.6}