Question

A reaction, A + B → C + D + q is found to have a positive entropy change. The reaction will be 

(i) possible at high temperature 

(ii) possible only at low temperature 

(iii) not possible at any temperature 

(iv) possible at any temperature 

Answer 1

For a reaction to be spontaneous, ∆G should be negative. 

∆G = ∆H – T∆S 

According to the question, for the given reaction, 

∆S = positive 

∆H = negative (since heat is evolved) 

⇒ ∆G = negative Therefore, the reaction is spontaneous at any temperature. 

Hence, alternative (iv) is correct.