Two moles of `PCl_5 ` are heated at `327^(@)`C in a closed vessel of volume 21. When equilibrium is established, it is found that 40% of `PCl_5` has dissociated into `PCl_3` and `Cl_2` . Calculate the equilibrium constant for the reaction.

Explanation

`PCl_5(g) Initial number of moles : 2 0 0
No. of moles at equilibrium: `(2-2xx(40)/(100))0.8" "0.8`
`:.[PCl_5]=(1.2)/(2)=0.6mol*L^(-1)`
`[PCl_3]=(0.8)/(2)=0.4mol*L^(-1)=[Cl_2]`
`K_c=([PCl_3][Cl_2])/([PCl_5])=(0.4xx0.4)/(0.6)=0.267mol*L^(-1)`