Topic : Chemistry Aim : Explain the different types of phase changes.
Jan 03, 2016
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.