What is defined as critical temperature for a gas?

The critical temperature of a gas is defined as the highest temperature at which the gas can exist as a liquid, regardless of the pressure applied. Above this temperature, the kinetic energy of the molecules is so high that they cannot be condensed into a liquid, no matter how much pressure is applied. When a substance is heated beyond its critical temperature, it enters a supercritical state where it displays properties of both gases and liquids.

This concept is crucial in understanding phase transitions and the behavior of substances under various temperature and pressure conditions. It helps in predicting whether a substance can be liquefied and is essential for practical applications in industries such as refrigeration, chemical manufacturing, and the study of materials. Understanding this temperature allows scientists and engineers to effectively manipulate and utilize gases in different processes.