Question

When KCl dissolves in water (assume endothermic dissolution), then :

• A. DH = + ve, DS = + ve, DG = + ve
• B. DH = + ve, DS = – ve, DG = – ve
• C. DH = + ve, DS = + ve, DG = – ve
• D. DH = – ve, DS = – ve, DG = + ve

Answer 1

Answer: (C)

DH = + ve, DS = + ve, DG = – ve

Answer 2

Some solids dissolves exothermically as LiCl (DH = –ve) and other dissolved endothermically as KCl

($\Delta$H = +ve). solvent-solvent interaction and solute-solute interaction are endothermic while solvent-solute interaction is exothermic. The sum of the three interaction determines whether $\Delta$Hsol is endothermic or exothermic.