Question

The vapour density of mixture of ${PCl}_5$, ${PCl}_3$ and ${Cl}_2$ is $92$. Find the degree of dissociation of ${PCl}_5$

Answer 1

Given :-

${PCl}_5\rightleftharpoons {PCl}_3+{Cl}_2$

${\left(C\right)}_{(1-x)}$ ${\left(Cx\right)}_{\left(x\right)}$ ${\left(Cx\right)}_{\left(x\right)}$

Let the initial concentration be ${}^{\prime }{c}^{\prime }$.

Concentration of ${PCl}_3=C-C_x$

where ${}^{\prime }{x}^{\prime }$ is the degree of dissociation $\left(\alpha \right)$

Total mole at equilibrium $=C+Cx$

initial mole $=C$

Therefore, degree of dissociation $\left(\alpha \right)$ is

$C+C\times /C=104.25/92$

$1+x=1.13$

$x=1.13-1$

$x=0.13$

$\therefore$ The degree of dissociation is $0.13$.