Changing States

:Solid becomes liquid.

–Energy is added

-Particles speed up.

-Temperature rises

Melting point: Temperature at which a substance changes from a solid to a liquid.

–Add heat to a liquid

•Atoms gain energy.

•Move faster

–Evaporation

•Particles can escape from the surface of a liquid if enough heat is added.

–Change in state from a gas directly to a solid.

•Substance cools.

•Atoms lose energy

•No liquid forms in the process.

•Example:

–Water vapor turns into ice crystals.

–Change in state from a solid directly into a gas. (skips liquid phase)

•Add heat

•Atoms gain energy

•Escape into the air as a gas.

•Example: Dry Ice

–Process by which liquids or solids change to a gas.

–Liquid becomes solid.

–Loss of energy.

•Particles slow down

•Temperature cools

–Freezing point

•Temperature at which a substance changes into a solid.

•Water = 0C or 32F

–The change in state from a gas to a liquid.

•Cooling a gas

•Particles lose energy.

–A rapid change from a liquid to a gas (vapor)

–Boiling Point

•The temperature at which this occurs in a liquid.

–100°C

–212°F