When an ideal solution is formed process is spontaneous. According to Raoult's law, for an ideal solution, ∆H=0,∆V‌mix ‌=0. Since, there is no exchange of heat energy between system and surroundings. ‌ i.e. ‌∆S‌System ‌=+‌ ve ‌ ⇒∆S‌Surrounding ‌=0 ‌ For the relation; ‌ ‌ Gibbs free energy; ‌∆G=∆H−T∆S ‌‌‌‌‌∆G=(0)−(+) ∆G=−‌ ve (for spontaneous process) ‌ ‌ Hence, ‌∆G=−‌ ve, ‌∆H=0,∆S‌System ‌=+‌ ve, ‌ ∆S‌Surrounding ‌=0