Question

In a $500 \, mL$ flask, the degree of dissociation of $PCl_5$ at equilibrium is $40\%$ and the initial amount is $5$ moles. The value of equilibrium constant in $mol \, L^{-1}$ for the decomposition of $PCl_5$ is

• A. 2.33
• B. 2.66
• C. 5.32
• D. 4.66

Answer 1

Answer: (B)

$\alpha=40 \%$
$=0.4$
$K_{c}=\frac{P C l_{3} Cl _{2}}{P C l_{5}}$
$=\frac{\frac{5 \times 0.4}{0.5 \times 0.5}}{\frac{5 \times 0.6}{0.5}}=\frac{16}{6}$
$=2.66\, mol / L$