Phase Change

• Adding or removing thermal energy increases or decreases the kinetic energy

  of the particles until a change of state occurs.

  • The change occurs between solid, liquid, and gas states of matter.

Changes Between Solid and Liquid

• Freezing: Change from liquid to solid

  • At its freezing temperature, the particles of a liquid begin to slow down

    and form more regular, stable patterns.

• Melting: Change from solid to liquid

  • At its melting point, particles of a solid begin to move quickly and break

    free from their fixed positions.

Changes Between Liquid and Gas

• Condensation: change from gas to liquid

  • Condensation occurs when particles in a gas lose enough thermal energy

    to form a liquid.

• Vaporization: change from liquid to gas

  • Vaporization takes place when the particles in a liquid gain enough thermal

    energy to form a gas.

Changes Between Liquid and Gas

• Types of Vaporization

  • Evaporation

    • Vaporization that occurs on the surface of a liquid.

  • Boiling

    • Vaporization that takes place below the surface of a liquid.

Changes Between Solid and Gas

• Sublimation: change from solid to gas

  • Particles of a solid do not pass through the liquid state as they form a gas.

    • Example: Dry Ice

• Deposition: change from gas to solid

  • Particles of a gas do not pass through the liquid state as they form a solid.

    • Example: Morning frost on he ground (water vapor → ice )

Phase Change Diagram (A)

Phase Change Diagram (B)