Question

One mole of $A_{\left(g\right)}$ is heated to ${300}^{0}C$ in a closed one litre vessel till the following equilibrium is reached. $A_{\left(g\right)}⟺B_{\left(g\right)}$. The equilibrium constant of the reaction at ${300}^{0}C$ is $4$. What is the conc. of $B(inmole.{lit}^{-1})$ at equilibrium?

• A. $0.2$
• B. $0.6$
• C. $0.8$
• D. $0.1$

Answer 1

The correct option is C $0.8$

Solution:- (C) $0.8$

$\underset{\text{At equillibrium}}{\underset{\text{Initially}}{}}\underset{(1-x)}{\underset{1}{A_{\left(g\right)}}}\rightleftharpoons \underset{x}{\underset{0}{B_{\left(g\right)}}}$

Given that:-

$K_c=4$

From the above reaction-

$K_c=\frac{\left[B\right]}{\left[A\right]}$

$\Rightarrow 4=\frac{x}{1-x}$

$\Rightarrow 4-4x=x$

$\Rightarrow x=\frac{4}{5}=0.8$

$\therefore$ equillibrium concentration of $B$ $=x=0.8\text{mol}{L}^{-1}$

Hence the equillibrium concentration of $B$ is $0.8mol/L$