Critical point

Definition

The critical point is the highest temperature and pressure at which a substance can exist as a liquid and gas in equilibrium. Beyond this point, the substance becomes a supercritical fluid with properties of both gas and liquid.

5 Must Know Facts For Your Next Test

1. Above the critical temperature, no amount of pressure can liquefy a gas.
2. The critical point marks the end of the phase boundary between liquid and gas phases.
3. Critical points are unique to each substance and depend on molecular interactions.
4. Supercritical fluids have unique solvating properties useful in various industrial applications.
5. The critical pressure is the minimum pressure required to liquefy a substance at its critical temperature.

Review Questions

• What happens to a substance when it is above its critical temperature?
• Why is the critical point significant in phase diagrams?
• How do supercritical fluids differ from liquids and gases?

Related terms

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.

Triple Point:

$The specific temperature and pressure where three phases (solid, liquid, gas) coexist in equilibrium.$