Question

For the following Reaction,
$H_{2\left(g\right)}+I_{2\left(g\right)}\rightleftharpoons 2H{I}_{\left(g\right)}$ ,
If initially $25\text{ml}$ of $H_2$ and $20\text{ml}$ of $I_2$ are present in a container and at equlibrium $30\text{ml}$ of $HI$ is formed then calculate the equlibrium constant:

• A. $50$
• B. $45$
• C. $18$
• D. $30$

Answer 1

The correct option is C $18$

The given Reactions,
$H_{2\left(g\right)}+I_{2\left(g\right)}\rightleftharpoons 2H{I}_{\left(g\right)}$
$t_{0}25ml20ml0$$t_{eq}25-x20-x2x$
Given, $2x=30\text{ml}$ so $x=15\text{ml}$
Equilibrium constant calculated as,
$K_c=\frac{[HI{]}^2}{\left[H_2\right]\left[I_2\right]}=\frac{[30{]}^2}{\left[10\right]\left[5\right]}=\frac{900}{50}=18$