Isotherms of carbon dioxide gas are shown in the given Fig 5.7. mark a path for changing gas into liquid such that only one phase (I.e., either a gas or liquid) exists at any time during the change. Explain how the temperature, volume and pressure should be changed to carry out the change.

Question

Isotherms of carbon dioxide gas are shown in the given Fig 5.7. mark a path for changing gas into liquid such that only one phase (I.e., either a gas or liquid) exists at any time during the change. Explain how the temperature, volume and pressure should be changed to carry out the change.

Philoid · Accepted Answer

In the given figure, we can move from A to F vertically by increasing the temperature, then we can reach the point G by compressing the gas at constant temperature along the isotherm, the pressure will increase. Now, move vertically down towards D by lowering the temperature.

As soon as we will cross the point H on critical isotherm, we get liquid. If the process is carried out at the critical temperature, substance always remain in one phase only. This is known as the continuity of state between the gaseous and liquid state.