[kirushanth]

If my understanding of critical temperature is correct, then at a temperature above the critical temperature, the gas cannot be converted into a liquid under any amount of pressure So what happens to the gas as we keep increasing the pressure?

Also, this must mean that at high temperatures, the vapor pressure of the gas is not defined. Is this right?

[vansh123]

The definition of Critical temp. which I understand is:
Critical temp. is that temp above which the gas cannot be liquified howerver large the pressure is applied.
Which means nothing will happen to the gas after the increase in pressure.
Yes that is right.

[Enthalpy]

When you increase the pressure of a gas a constant temperature:
- Below the critical point, at some pressure that depends on the temperature, some of the gas coalesces into a liquid fraction. At this constant temperature, pressure is constant, and the proportion of liquid depends on the volume you give.
- Above the critical point, the temperature is stronger than the attraction between the molecules, and no liquid forms.

Though, enough pressure will get the gas' density very similar to a liquid, and you will still observe a dip in the gas' density curves near the critical temperature, but no liquid separates from the gas.

These are typical conditions (density similar to the liquid) where laws of perfect gas do not apply.

[curiouscat]

1. You'll see no abrupt transition from G to L. i.e. no phase change.
2. G will smoothly transition into a Supercritical fluid.