At `473 K`, equilibrium constant `K_(c )` for decomposition of phosphorus pentachloride, `PCl_(5)` is `8.3xx10^(-3)`. If decomposition is depicted as,
`PCl_(5)(g) hArr PCl_(3)(g)+Cl_(2)(g) Delta_(r)H^(Θ)=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

(a) The expression for `K_(c) = [[PCI_(3)(g)][CI_(2)(g)]]/[[PCI_(5)(g)]]`
(b) For reverse reaction `(K_(c)) = (PCI_(5)(g))/[[PCI_(3)(g)][CI_(2)(g)]] =(1)/(8.3 xx 10^(-3)) =120.48`
(c) (i) By adding more of `PCI_(5)` value of `K_(c)` wil remain constant because there is no change in temperature .
(ii) By increasing the temperature , the forward reaction will be favoured since it is endothermic in nature. Therefore , the value of equilibrium constant will increase.