The phase change of water is the process by which water transitions from one state of matter to another, such as from a liquid to a solid or from a gas to a liquid.
The boiling point of water is the temperature at which water changes from a liquid to a gas. It is 100 degrees Celsius or 212 degrees Fahrenheit at sea level.
The pressure required for water to phase change depends on the temperature of the water. For example, at sea level, water will boil at 100 degrees Celsius when the atmospheric pressure is 1 atm. However, at higher altitudes where the atmospheric pressure is lower, water will boil at a lower temperature.
The critical point of water is the temperature and pressure at which liquid and gas phases of water become indistinguishable and form a homogeneous fluid. For water, the critical point is 374 degrees Celsius and 218 atmospheres of pressure.
Yes, water can exist in a liquid state at extreme pressures. At high enough pressures, water can remain liquid even at temperatures above its boiling point. This is known as superheated water and is often used in industrial applications.