Question

At 473K equilibrium constant Kc for the decomposition of phosphorus pentachloride PCl₅ is 8.3 × 10⁻³. If the decomposition is depicted as:PCl₅ (g) ⇄ PCl₃ (g) + Cl₂ (g) ΔH = 124.0 kJ mol⁻¹a. Write an expression of Kc for the reactionb. What is the value of Kc for the reverse reaction at the same temperature?c. What would be the effect on Kc if (i) more PCl₅ is added (ii) pressure is increased (ii) temperature is increased

Answer 1

(a) 

(b) Value of Kc for the reverse reaction at the same temperature is: 



(c) (i) Kc would remain the same because in this case, the temperature remains the same. 

(ii) Kc is constant at constant temperature. Thus, in this case, Kc would not change. 

(iii)In an endothermic reaction, the value of Kc increases with an increase in temperature. Since the given reaction in an endothermic reaction, the value of Kcwill increase if the temperature is increased. 

Answer 2

(a)  

(b) Value of Kc for the reverse reaction at the same temperature is:  

(c) (i) Kc would remain the same because in this case, the temperature remains the same.  

(ii) Kc is constant at constant temperature. Thus, in this case, Kc would not change.  

(iii)In an endothermic reaction, the value of Kc increases with an increase in temperature. Since the given reaction in an endothermic reaction, the value of Kcwill increase if the temperature is increased.