Question

For the reaction; $A+B\rightleftharpoons 3C$, at ${25}^{o}C$, a $3$ litres vessel contains $1,2$ and $4$ moles of $A,B$ and $C$ respectively. If $K_c$ for the reaction is $10$, the reaction will proceed in :

• A. forward reaction
• B. backward direction
• C. either direction
• D. equilibrium

Answer 1

The correct option is B backward direction

Quotient $Q=\frac{{\left[C\right]}^3}{\left[A\right]\left[B\right]}=\frac{4^3\times 3\times 3}{3^3\times 1\times 2}=10.66$

$[\left[C\right]=\frac{4}{3};\left[A\right]=\frac{1}{3};\left[B\right]=\frac{2}{3}]$

Since, $K_c=10$. Thus, $Q$ must decrease to attain value of $K_c$ and therefore $\left[C\right]$ must decrease or $\left[A\right]$ or $\left[B\right]$ must increase, i.e., backward direction.

So, the correct option is $B$