Question

What is the critical temperature of water?

Answer 1

Hint: Critical temperature of water or any liquid is defined as the maximum temperature range at which gas can be easily liquified by applying pressure over it. above critical temperature liquefaction of gas is not feasible no matter how much pressure we applied over it.

Complete answer:
Critical temperature of water is defined as a thermodynamic property of liquid. A graph is plotted between pressure and temperature of water to describe the critical point, critical temperature as well as critical pressure of water.
As we know water exists as solid, liquid as well as its gaseous form. But gaseous water converted to its liquid form only under a particular temperature range. Because as we gradually increase the temperature of water its gaseous molecule gets more kinetic energy and does not get liquified easily.

Every single substance has a specific value of critical temperature and critical pressure. Water has a value of critical temperature of which is also expressed in degree Celsius as ${393.946^ \circ }C$.
In the absence of any critical temperature, physical properties of water and water vapor changes unexpectedly. Physical properties of water before critical point include low thermal expansion coefficient of water, high value of dielectric constant, etc. However, beyond the critical point all these $647.096{\rm K}$ properties change into opposite properties like water becoming expandable, low dielectric property, bad solvent.
$ \Rightarrow $ Critical temperature of water is $647.096{\rm K}$ or ${393.946^ \circ }C$

Note:
Water exists only in one phase at its critical temperature. The heat of vaporization of water at its critical temperature is considered as zero. Supercritical fluids exist beyond the critical temperature. Critical pressure is also used to describe the liquefiable property of liquid at specific pressure.