Question

In a closed cylinder of capacity $24.6L$, the following reaction occurs at $27^{\circ }C$.
$A_2(s)\rightleftharpoons B_2(s)+2C(g)$
At equilibrium, $1g$ of $B_2(s)$ (molar mass $=50gmo{l}^{-1}$ ) is present. The equilibrium constant $K_p$ for the equilibrium in atm ${}^2$ unit is
$\left(R=0.082Latm{K}^{-1}mo{l}^{-1}\right)$

• A. $1.6\times 10^{-2}$
• B. $1.6\times 10^{-5}$
• C. $1.6\times 10^{-3}$
• D. $1.6\times 10^{-4}$
• E. $1.6\times 10^{-1}$

Answer 1

Answer: (C)

Equilibrium concentration of $B_2$,

${\left[B_2\right]}_{\text{equilibrium }}=\frac{\text{ mass }}{\text{ molar mass }\times \text{ volume }}$

$=\frac{1}{50\times 24.0}=8.13\times 10^{-4}$

For the reaction,



$\therefore [C]=2\times 8.13\times 10^{-4}=1.63\times 10^{-3}$

$K_c=[C{]}^2={\left[1.63\times 10^{-3}\right]}^2=2.66\times 10^{-6}$

Again from, $K_p=K_C(KT{)}^{\Delta n_y}$

Here, $\Delta n_g=2-0=2$

$K_p=2.66\times 10^{-6}\times (0.082\times 300{)}^2$

$\approx 1.6\times 10^{-3}$