At `473 K`, equilibrium constant `K_(c)` for decomposition of phosphorus pentachloride, `PCl_(5)` is `8.3 xx 10^(-3)` . If decomposition is depicted as,
`PCl_(5)(g) hArr Pcl_(3)(g) + Cl_(2) , Delta_(r)H^(ɵ) = 124.0 kJ "mol"^(-1)`
a) write an expression for `K_(c)` for the reaction.
b) what is the value of `K_(c)` for the reverse reaction at the same temperature ?
c) what would be the effect on `K_(c)` if (i) more `PCl_(5)` is added (ii) pressure is increased (iii) the temperature is increased ?

Explanation

At a constant temperature, the value of` K_c` is not affected by addition of reactants. Therefore, `K_c` will remain unchanged.
(ii)` K_c` will remain unchanged.
(iii) Since` K_c= (K_1)/(K_2)` an increase in temperature will favour
the forward reaction as the reaction is endothermic. Thus, k1 will increase. Hence, the value of Kc will increase on increasing temperature.