The equilibrium constant for the reaction $\mathrm{HI}\left(\mathrm{g}\right)\rightleftharpoons \frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{I}}_2\left(\mathrm{g}\right)$  is 7.4. The value of equilibrium constant of the reaction $2\mathrm{HI}\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{I}}_2\left(\mathrm{g}\right)$ will be

$K_{\text{new }}={\left(K_{\text{old }}\right)}^2={7.42}^2=54.76$

A number that represents the proportionality of the reactant and product concentrations at equilibrium in a reversible chemical reaction at a certain temperature.