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# Phase Diagram

Freezing is the phase change as a substance changes from a liquid to a solid.

Melting is the phase change as a substance changes from a solid to a liquid.

Condensation is the phase change as a substance changes from a gas to a liquid.

Vaporization is the phase change as a substance changes from a liquid to a gas.

Sublimation is the phase change as a substance changes from a solid to a gas without passing through the intermediate state of a liquid.

Deposition is the phase change as a substance changes from a gas to a solid without passing through the intermediate state of a liquid.

TRIPLE POINT - The temperature and pressure at which the solid, liquid, and gas phases exist simultaneously.

CRITICAL POINT - The temperature above which a substance will always be a gas regardless of the pressure.

Supercritical Fluid Xenon above 16oC

Liquid Xenon heated up to 20 C and become a supercritical.

Liquid Chlorine immersed into hot oil bath (ca 160C) and became supercritical. After cooling down it condensing back into liquid.
Critical temperature of the Chlorine - 143.8°C, critical pressure - 76.0 atm
Diameter of the ampule - 4 mm

The line between the solid and liquid phases is a curve of all the freezing/melting points of the substance.

The line between the liquid and gas phases is a curve of all the boiling points of the substance.

Freezing Point - The temperature at which the solid and liquid phases of a substance are in equilibrium at atmospheric pressure.

Boiling Point - The temperature at which the vapor pressure of a liquid is equal to the pressure on the liquid.

Normal (Standard) Boiling Point - The temperature at which the vapor pressure of a liquid is equal to standard pressure (1.00 atm = 760 mmHg = 760 torr = 101.325 kPa)

Density determinations from phase diagrams

The solid phase is more dense than the liquid phase. The line that separates solid and liquids bends right.

IF the solid phase is less dense than the liquid phase. The line that separates solid and liquids bends left.

NOTE-Since Ice is less dense than water (it floats remember), the line that separates solid and liquids bends to the left. So when the pressure increase on ice it will melt.