Question

In a $0.5$ litre capacity vessel, $CO$ and $Cl _{2}$ are mixed to form $COCl _{2} .$ At equilibrium, it contains $0.2$ mole of $COCl _{2}$ and $0.1$ mole each of $CO$ and $Cl _{2}$. The equilibrium constant $\left( K _{ c }\right)$ for reaction $CO + Cl _{2} \rightleftharpoons COCl _{2}$ is

• A. 15
• B. 5
• C. 20
• D. 10

Answer 1

Answer: (D)

In this reaction,
Number of moles of $COCl _{2}=0.2$
Number of moles of $CO =0.1$
Number of moles of $Cl =0.1$
The concentration of $COCl _{2}$
$=\frac{\text { Number of moles }}{\text { Volumes in litres }}=\frac{0.2}{0.5}=0.4 \,mol\, L ^{-1}$
Concentration of $CO =\frac{0.1}{0.5}=0.2\, mol\, L ^{-1}$
Concentration of $Cl =\frac{0.1}{0.5}=0.2\, mol\, L ^{-1}$
The equilibrium constant of the reaction
$K _{ c }=\frac{\left[ COCl _{2}\right]}{[ CO ]\left[ Cl _{2}\right]}=\frac{0.4}{0.2 \times 0.2}=10$