Critical pressure

Definition

Critical pressure is the minimum pressure required to liquefy a gas at its critical temperature. It marks the endpoint of the liquid-vapor phase boundary.

5 Must Know Facts For Your Next Test

1. Critical pressure is specific to each substance and varies based on molecular characteristics.
2. At the critical pressure and critical temperature, the substance exists as a supercritical fluid with properties of both liquid and gas.
3. Water's critical pressure is approximately 22.064 MPa (megapascals).
4. Above the critical pressure, increasing temperature does not cause a phase change from liquid to gas.
5. The concept of critical pressure is crucial for understanding phase diagrams and predicting phase changes in gases.

Review Questions

• What happens to a substance when it reaches its critical pressure and critical temperature?
• How does critical pressure differ between various substances?
• Why does increasing temperature above the critical point not result in a phase change?

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 a substance as a function of temperature and pressure.

Supercritical Fluid: A state of matter beyond the critical point where distinct liquid and gas phases do not exist.