What is Critical Temperature?
Critical temperature is the temperature above which a gas cannot be liquefied, regardless of the pressure applied to it. It is the highest temperature at which the gas can be condensed into a liquid state.

Why Gas Cannot be Liquefied at Critical Temperature?
- At temperatures below the critical temperature, a gas can be liquefied by applying pressure. However, at the critical temperature, the distinction between the liquid and gas phases disappears, and the substance is said to be in a supercritical state.
- When a gas is heated to its critical temperature, the kinetic energy of the gas molecules becomes so high that the intermolecular forces are unable to hold the molecules together in a condensed liquid state.
- At the critical temperature, the density of the gas is very close to that of the liquid, making it impossible to distinguish between the two states. This results in a supercritical fluid that exhibits properties of both a gas and a liquid.
- Therefore, no matter how much pressure is applied to a gas at its critical temperature, it will not condense into a liquid. This is because the molecules are moving too fast to be held together by intermolecular forces.
- Understanding the concept of critical temperature is important in various fields such as chemistry, physics, and engineering, as it helps in predicting the behavior of substances under different conditions.
In conclusion, the critical temperature is a crucial parameter that determines the behavior of a substance at high temperatures and pressures, and it plays a significant role in understanding the phase transitions of gases.