(c) phase change at constant temperature and pressure

Melting :   [ solid to liquid]

Evaporation: [ liquid to vapor]

(d) Change of state for an ideal gas

If an ideal gas undergoes a change of state from to

(22.11)

or,

(22.12)

or,

(22.13)

or,

or,

ln

(22.14)

Again,

or,

(22.15)

or,

(22.16)

or,

(22.17)

or,

(22.18)

ln ln

(22.19)

For a constant temperature process is either ln or, ln .