Question

True or False: Mercury vapor must have a negative standard enthalpy of formation

True or False: A perfect gas will not change temperature if isoenthalpically compressed, but will cool if adiabatically (and reversibly) expanded.

True or False: Deposition of a pure substance under isochoric conditions is endothermic.

Answer 1

Ans: 1) Mercury vapor must have a negative standard enthalpy of formation

False, Because the pure element has zero standard enthalpy of formation as there is no any change.

2) A perfect gas will not change temperature if isoenthalpically compressed, but will cool if adiabatically (and reversibly) expanded

False, Because If mu > 0, as P increases at constant enthalpy then T must also increase.

3) Deposition of a pure substance under isochoric conditions is endothermic

True