28. The value of Kc for the reaction $2\mathrm{HI}\left(\mathrm{g}\right)⇌{\mathrm{H}}_{2}\left(\mathrm{g}\right)+{\mathrm{I}}_{2}\left(\mathrm{g}\right)$ is $1×{10}^{-4}$. At a given time, the composition of reaction mixture is  and . In which direction will the reaction proceed?

Given that,

At a given time, the reaction quotient Q for the reaction will be given by the expression
$\mathrm{Q}=\frac{\left[{\mathrm{H}}_{2}\right]\left[{\mathrm{I}}_{2}\right]}{{\left[\mathrm{HI}\right]}^{2}}\phantom{\rule{0ex}{0ex}}=\frac{1×{10}^{-5}×1×{10}^{-5}}{{\left(2×{10}^{-5}\right)}^{2}}=\frac{1}{4}\phantom{\rule{0ex}{0ex}}=0.25=2.5×{10}^{-1}$
As the value of reaction quotient is greater than the value of Kc, i.e., $1×{10}^{-4}$ the reaction will proceed in the reverse reaction.