One mole of N2 and 3 moles of PCl5 are placed in a 100 litre vessel heated to 227∘C. The equilibrium pressure is 2.05 atm. Assuming ideal behaviour, calculate degree of dissociation of PCl5 for the reaction PCl5⇌PCl3+Cl2.
33.3 %
N2+PCl5⇌PCl3+Cl2
\begin{array}{c c c}
\text{ Moles at t = 0 } & \text{1} & \text{3} & \text{0} & \text{0} \\
\text{Moles} & \text{1} & \text{(3-x)} & \text{x} & \text{x} \\
\end{array}
at equilibrium
Total moles present at equilibrium = 4 + x
Given total pressure at equilibrium = 2.05
PV = nRT
2.05×100=(4+x)×0.082×500
x = 1.0
Degree of dissociation ′α′ for PCl5
=Moles dissociatedTotal moles present=13=0.3333=33.33