Question

The reaction $A+B\rightleftharpoons C+D$ is studied in a one litre vessel at ${250}^{\circ }C$. The initial concentration of A was 3n and that of B was n. When equilibrium was attained, the equilibrium concentration of C was found to the equal to the equilibrium concentration of B.

What is the concentration of D at equilibrium :

• A. n/2
• B. (3n - 1/2)
• C. (n - n/3)
• D. n

Answer 1

Answer: (A)

n/2

$A+B\rightleftharpoons C+D$

$t=0$ 3n n 0 0

$t=\infty$ 3n-x n-x x x

$n-x=x$

$2x=n$

$x=\frac{n}{2}$ i.e.$[D{]}_{eq}.=\frac{n}{2}$

So, the correct option is $A$