Question

${PCl}_3\left(g\right)+{Cl}_2\left(g\right)\rightleftharpoons {PCl}_5\left(g\right)+energy$
What is the equilibrium expression for the reaction shown above?

• A. $\frac{\left[PC{l}_5\right]\left[PC{l}_3\right]}{\left[C{l}_2\right]}$
• B. $\frac{\left[{PCl}_3\right]\left[{PCl}_2\right]}{\left[{PCl}_5\right]}$
• C. $\frac{\left[{PCl}_3\right]\left[{PCl}_2\right]}{\left[{PCl}_5\right]\left[energy\right]}$
• D. $\frac{\left[{PCl}_5\right]}{\left[{PCl}_3\right]\left[{Cl}_2\right]}$
• E. $\frac{\left[PC{l}_3\right]\left[C{l}_2\right]}{\left[PC{l}_5\right]}$

Answer 1

Answer: (D)

$\frac{\left[{PCl}_5\right]}{\left[{PCl}_3\right]\left[{Cl}_2\right]}$

The given reaction is :-

${PCl}_3\left(g\right)+{Cl}_2\left(g\right)\rightleftharpoons {PCl}_5\left(g\right)+energy$

$\therefore K_C=\frac{\left[{PCl}_5\right]}{\left[{PCl}_3\right]\left[{Cl}_2\right]}$

Hence, option $\left(D\right)$ is correct.