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) K_(c) = [PCl_(3)][Cl_(2)]/[PCl_(5)]`
(b)`K' = 1/K_(c) = 1/(8.3 xx 10^(-3)) = 120.48`
(c ) (i) No effect as Kc is constant at constant temperature
(ii) No effect
(iii) As given reaction is endothermic, on increasing the temperature,`k_(f)` will increase.
As `K_(c) = k_(f)/k_(c)` ,Kc will increases with increases of temperature.