topic: chemistry aim: explain the different types of phase changes

Topic: ChemistryAim: Explain the different types of phase changes.

Review:1. Identify the different phases of matter.2. The particles of a substance are closest

together in a _____.3. The particles of a substance that does

not have a definite volume or shape is4. Identify an example of a physical

change.5. What are 2 physical properties of

matter?6. Give 1 example of a chemical property.

Phase Changes• Involves the

absorption or release of heat (energy).

1. Melting•Solid liquid

• Melting point: temp at which a solid changes to liquid (different for every substance)

Substance absorbs heat energy

2. Freezing• Liquid solid

• Freezing point: temp at which substance changes from liquid to solid

Substance loses heat energy

3. Evaporation

LIQUID

GASLiquid absorbs heat energy

• Liquid gas

• Boiling point: temp at which liquid boils (different for every substance)

4. Condensation•Gas liquid

LIQUID

GASGas loses heat energy

5. Sublimation•Solid Gas• No liquid phase• Ex: dry ice

Solid

GASSolid absorbs heat energy

Freezing

LS

Melting SL

Evaporation LG

Condensation GL

Add heat Energy absorbed by molecules

Remove heat Energy released by molecules

PHASE CHANGES

SOLID LIQUID GAS

Time

T

E

M

P

Freezing/melting point = 0°C

Boiling pt =

100°C

SO

LID

LIQ

UID

GAS

100°C

0°C

Melting

Freezing

Evaporation

Condensation

PHASE CHANGE GRAPH FOR WATER

= phase changes

REVIEW:1. When a liquid becomes a solid, energy

____.2. ____ is the process in which liquid

changes to gas below the boiling point. 3. The change of a liquid to a solid is

called__.4. What happens to the position of water

molecules as they lose heat energy?5. Identify one phase change in which

energy is released.

1. Melting•Solid liquid• Heat added/absorbed • molecules move faster & farther apart• Melting point: temp at which a solid changes to liquid (different for every substance)

Substance absorbs heat energy

2. Freezing• Liquid solid• Liquid heat energy/energy released • Molecules slow down & come closer together• Freezing point: temp at which substance

changes from liquid to solid

Substance loses heat energy

3. Evaporation

LIQUID

GASLiquid absorbs heat energy

• Liquid gas• Heat added/absorbed (faster & farther)• On surface of liquid evaporation• Boiling point: temp at which liquid

boils (different for every substance)

4. Condensation•Gas liquid• Gas loses heat energy/energy

released• (slow down & closer together)

LIQUID

GASGas loses heat energy

Moth balls commonly undergo the process of sublimation. Sublimation is the process in which a solid changes directly to its gaseous phase, skipping the liquid phase.