Starting with the fundamental equation of thermodynamics, and using the data below:

	H	G	S	Cp
Water	-285.8 kJmol-1	-237.1 kJmol-1	69.9 JK-1mol-1	75.3 JK-1mol-1
Water Vapour	-241.8 kJmol-1	-228.6 kJmol-1	188.3 JK-1mol-1	33.6 JK-1mol-1

1. Derive an expression for the change in Gibbs energy of vaporisation with temperature for water assuming a constant pressure of 1 bar. Thus calculate the temperature at which vaporisation becomes thermodynamically favourable and comment on the accuracy of this calculation.

[2 marks]

2. Derive an expression for the change in Gibbs energy of vaporisation with pressure for water assuming a constant temperature of 298.15 K. Thus calculate the pressure at which vaporisation becomes thermodynamically favourable.

[2 marks]