Critical pressure

Definition

Critical pressure is the minimum pressure required to liquefy a substance at its critical temperature. It is a specific point where the distinction between liquid and gas phases ceases to exist.

5 Must Know Facts For Your Next Test

1. Critical pressure is unique for each substance.
2. It marks the end of the liquid-vapor boundary in a phase diagram.
3. Beyond critical pressure, a substance becomes a supercritical fluid.
4. Water has a critical pressure of approximately 22.1 MPa (megapascals).
5. Critical pressure and critical temperature together define the critical point on a phase diagram.

Review Questions

• What happens to a substance when it reaches its critical pressure and temperature?
• Why is critical pressure important in understanding phase changes?
• How does the critical pressure of water compare to other common substances?

Related terms

Critical Temperature: The highest temperature at which a substance can exist as a liquid, regardless of pressure.

Phase Diagram:

A graphical representation showing the phases of matter as functions of temperature and pressure.

Supercritical Fluid:

A state of matter beyond its critical point, where it exhibits properties of both liquids and gases.