Question

At a certain temperature in a $5$L vessel, $2$ moles of carbon monoxide and $3$ moles of chlorine were allowed to reach equilibrium according to the reaction, $CO+C{l}_2\rightleftharpoons COC{l}_2$
At equilibrium, if one mole of $CO$ is present then equilibrium constant $\left(K_c\right)$ for the reaction is:

• A. $2.5$
• B. $4$
• C. $2$
• D. $3$

Answer 1

The correct option is A $2.5$

Initially, 2 moles of CO are present.

At equilibrium, 1 mole of CO is present.

Hence, $2-1=1$ mole of CO has reacted.

1 mole of CO will react with 1 mole of $C{l}_2$ to form 1 mole of $COC{l}_2$.

$3-1=2$ moles of $C{l}_2$ remains at equilibrium.

The equilibrium constant
$K_c=\frac{\left[COC{l}_2\right]}{\left[CO\right]\left[C{l}_2\right]}$

$K_c=\frac{\frac{\text{1 mol}}{\text{5 L}}}{\frac{\text{1 mol}}{\text{5 L}}\times \frac{\text{2 mol}}{\text{5 L}}}$

$K_c=2.5$

Option A is correct.