phase changes. review: 3 phases of matter solid liquid gas
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Phase Changes
Review: 3 Phases of Matter
• Solid
• Liquid
• Gas
What is a Phase Change?
• Is a change from one state of matter (solid, liquid, gas) to another.
• Phase changes are physical changes because:- It only affects physical appearance, not
chemical make-up.
- Reversible
What happens during a phase change?
• During a phase change, heat energy is either absorbed or released.
• Heat energy is released as molecules slow down and move closer together.
• Heat energy is absorbed as molecules speed up and expand.
Types of Phase Changes
• Types of Phase Changes
Melting
• Phase change from a solid to a liquid
• Molecules speed up, move farther apart, and absorb heat energy
Freezing
• Phase Change from a liquid to a solid
• Molecule slow down, move closer together and release heat energy.
Vaporization (Boiling)
• Phase change from a liquid to gas. It occurs at the boiling point of matter.
• Molecules speed up, move farther apart, and absorb heat energy.
Evaporation
• Phase change from a liquid to a gas on the surface of a liquid (occurs at all temperatures).
• Molecules speed up, move farther apart, and absorb heat energy.
Condensation
• Phase change from a gas to a liquid.
• Molecule slow down, move closer together and release heat energy.
Sublimation
• Phase change from a solid to a gas.
• Molecules speed up, move farther apart, and absorb heat energy.
Deposition
• Phase change from a gas to a solid.
• Molecules slow down, move closer together and release heat energy.
Graphing a Phase Change
Melting & Boiling Points
• Melting Point: The temperature at which a solid changes into a liquid.
• Boiling Point: The temperature at which a liquid changes into a gas.
• What is a Freezing point? Compare the freezing and melting points of water.
Summary
Graphing a Phase Change– Why is there no change
in temperature during a phase change?
– Define melting and boiling points.
– What is the melting point and boiling point of water?
– At what temperature does water freeze and become a solid?
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