At 500 K , the equilibrium constant for the reaction $\mathrm{H}_{2(\mathrm{~g})}+\mathrm{I}_{2(\mat

Question

At 500 K , the equilibrium constant for the reaction $\mathrm{H}_{2(\mathrm{~g})}+\mathrm{I}_{2(\mathrm{~g})} \rightleftharpoons 2 \mathrm{HI}_{(\mathrm{g})}$ is 24.8 . If $\frac{1}{2} \mathrm{~mol} / \mathrm{L}$ of HI is present at equilibrium, what are the concentrations of $\mathrm{H}_2$ and $\mathrm{I}_2$, assuming that we started by taking HI and reached the equilibrium at 500 K ?

Professor PC Thomas Classes · Answer

(c) $\begin{aligned} K_c= & \frac{\left[\mathrm{H}_2ight]\left[\mathrm{I}_2ight]}{[\mathrm{HI}]^2} 	ext { or } \frac{1}{24.8}=\frac{x . x}{0.5 	imes 0.5} 	ext { or } x^2=\frac{0.25}{24.8}=0.010 \ & x=0.1 \mathrm{~mol} \mathrm{~L}^{-1}\end{aligned}$