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

Given: `PCI_(5)(g)hArrPCI_(3)(g)+CI_(2)(g)`,
(a) `K_(c)=([PCI_(3)(g)][CI_(2)(g)])/([PC|_(5)(g)`
Substitution & Calculation:
(b) `K'=(1_)/(K_(c))=(1)/(8.3xx10^(-3))=120.48`
(c) (i) No effect.
(ii) NO effect.
(iii) As given reaction is endothermic, on increasing the temperature, `K_(t)` will increase. As `K_(c)=(K_(t))/(K_(b)), K_(c)` will increase with increase of temperature.