Question

At a certain temperature in a 5L 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 equilibrum 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

$CO+C{l}_2\rightleftharpoons COC{l}_{2}230(2-1)(3-1)1$
Initially, 2 moles of $CO$ are present.
At equilibrium, 1 mole of $CO$ is present.
Hence, 2 -1 = 1 mole $CO$ has reacted.

1 mole of $CO$ will react with 1 mode of ${Cl}_2$ to form 1 mole of $COC{l}_2$,
$3-1=2$ moles of $C{l}_2$ remains at equlibrum.
Volume of vessel = 5L (Given)
The equilibrium constant

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

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

$K_c=2.5$
Option (a) is correct.