For the endothermic physical change of water (liquid) into water vapor (gas), describe the entropy change, the enthalpy change, and use Gibb’s Free Energy to explain when this reaction will be spontaneous and when it will not.

Answer 1

H2O(l) + heat ==> H2O(g)
dH is + (endothermic) and dS = + (more disorder in the gas than in the liquid)
dG = dH - TdS
If dG < 0 (negative) it is spontaneous
If dG > 0 (positive) it is not spontaneous