Question

Comment on the validity of the following statements, giving reasons`:`
(i) Thermodynamically, an exothermic reaction is sometimes not spontaneous.
(ii) The entropy of steam is more than that of water at its boiling point.
(iii)The equilibrium constant fora reaction isone or more if `Delta_(r)G^(@) ` for it is less than zero.

Answer 1

(i) Yes, the given statement is true. This is because `DeltaG= Delta H -T Delta S`.For exothermic reaction, `DeltaH` is `-ve`. If `T DeltaS` is`+ve` (i.e.,entropy factor opposes the process) and `T DeltaS gt DeltaH` in magnitude, `DeltaG` will be`+ve` and process will be spontaneous.
(ii) Yes, the given statement is true. This is because at the same temperature, gaseous state is more disordered than the liquid state.
(iii) `- DeltaG^(@) = RT `ln K. Thus, if `DeltaG^(@)` is less than zero, i.e., it is`-ve` , then ln K will be `+ve` and hence K will be greater than 1.