Question

An equilibrium system for the reaction between hydrogen and iodine to give hydrogen iodide at $765\, K$ in a $5$ litre volume contains $0.4$ mole of hydrogen, $0.4$ mole of iodine and $2.4$ moles of hydrogen iodide. The equilibrium constant for the reaction
$H_{2} + I_{2} \rightleftharpoons 2HI$ is

• A. $36.0$
• B. $15.0$
• C. $0.067$
• D. $0.028$

Answer 1

Answer: (A)

$H_{2} + I_{2} \rightleftharpoons 2HI$
At equilibrium $\frac {0.4}{5} \frac{0.4}{5} \frac{2.4}{5}$
$K_{c}=\frac{\left(\frac{2.4}{5}\right)^{2}}{\left(\frac{0.4}{5}\right)\left(\frac{0.4}{5}\right)} $
$K_{c} = \frac{2.4\times2.4 }{0.4\times0.4} $
$K_{c} =\frac{576}{0.16} $
$K_{c} = 36$