Question

Give reason: 

(i) Neither q nor w is a state function but q+w is a state function. 

(ii) The dissociation of ammonium chloride in water is endothermic still it dissolve in water. 

(iii) Areal crystal has more entropy than an ideal crystal.

Answer 1

(i) q+w =∆U. As ∆U is a state function, hence q+w is a state function. 

(ii) On dissociation ,entropy increases, i.e. ,∆S is +ve .Though ∆His +ve but if T∆S>∆H, then according to the equation, ∆G =∆H - T∆S,∆G will be –ve. Hence, the process is spontaneous. 

(iii) A real crystal has some disorder due to presence of defects whereas ideal crystal has no disorder . Hence ,a real crystal has more entropy then ideal crystal.