Question

Use the thermodynamic data provided below to determine ΔG (in kJ/mol) for the vaporization of CaO at 91.8 °C if the initial partial pressure of CaO is 1.76 atm. Report your answer to one decimal place in standard notation (i.e. 123.4 kJ/mol).

Substance		ΔH°f (kJ/mol)		S° (J mol-1K-1)
CaO (l)		-557.3		62.3
CaO (g)		43.9		219.7

Answer 1

For CaO (l)

G = H - TS

G = -557.3 kJ/mol - 364.95 (0.0623kJ mol^-1K^-1)

G = -580.36 kJ mol^-1

For CaO (l)

G = H - TS

G = 43.9 kJ mol^-1- 364.95 (0.219.7kJ mol^-1K^-1)

G = 43.9 - 80.18

G = 36.28 kJ mol^-1