Liquifasction occurs in different steps in same phase. - Explain with example.

Explanation

Process of convert gas into liquid or liquid into gas is possible in same phase.
e.g. : `A_((g))overset((i))rarr F_((g))overset((ii))rarr G_((g))overset((iii))rarr H_((l))rarr D_((l))`
Liquifaction occurs in three steps in same phase.

Step - (i) (Point A to Point F) : We can move from point A to F vertically by increasing the temperature, pressure also increases.
Step - (ii) (Point F to Point G) : We can reach the point F to G by compressing the gas at the constant temperature along this isotherm (Isotherm at `31.1^(@)C`). The pressure will increases.
Step - (iii) (Point G to Point D) : we can move vertically down towards G to D by lowering the temperature. As soon as we cross the point H on the critical isotherm we get liquid.
We end up with liquid but in this series of changes we do not pass through two phase region. If liquifaction is done by first critical temperature then substance situated always in one phase.