Post on 19-Jan-2015
description
Warm-Up (summarize!!)Warm-Up (summarize!!)
Water is an abundant substance on Earth. It can be found as a solid, a liquid, and as a gas called water vapor.
1. Write as many words you can think of to describe solid water?
2. Where is most of the liquid water on Earth found? Where is most of the water vapor found?
3. Describe a natural event you have observed when water changed from a liquid to a solid? When water changed from a liquid to a vapor?
2-8 Phase Change2-8 Phase Change
• ObjectivesObjectives– DescribeDescribe phase change. phase change.– DescribeDescribe each of the six phase each of the six phase changes.changes.
– ExplainExplain how temperature can be how temperature can be used to recognize a phase change.used to recognize a phase change.
– IdentifyIdentify phase changes as phase changes as endothermic or exothermic.endothermic or exothermic.
Phase Changes – Changes of Phase Changes – Changes of StateState
• Adding or removing energy Adding or removing energy (heat) to a substance causes (heat) to a substance causes phase changesphase changes
• During a phase change, During a phase change, temperature does temperature does NOTNOT change change
• Phase changes are reversible.Phase changes are reversible.
Types of Phase changesTypes of Phase changes
• VaporizationVaporization– changing liquid into gas.changing liquid into gas.– evaporation and boiling.evaporation and boiling.– Adding energyAdding energy
•CondensationCondensation-changing gas changing gas
into liquidinto liquid..-Removing energyRemoving energy
Types of Phase changesTypes of Phase changes
• SublimationSublimation– changing solid changing solid directly into gas directly into gas without becoming without becoming liquid.liquid.
– Adding energyAdding energy
•DepositionDeposition-changing gas changing gas directly into directly into solid.solid.-Removing energyRemoving energy
Types of Phase changesTypes of Phase changes
• MeltingMelting– changing solid changing solid into liquid.into liquid.
– Adding energyAdding energy
• FreezingFreezing– changing liquid changing liquid into solid.into solid.
– Removing energyRemoving energy
AB
-heat Δ KE
-move faster
-temp. -solid
BC
-heat Δ PE
-get farther apart
-temp. stay same
-melting
CD
-heat Δ KE
-move faster
-temp. -liquid
Solid
Melting
Liqui
d
Phase Change Graps (T vs t)Phase Change Graps (T vs t)
DE
-heat Δ PE
-get farther apart
-temp. stay same
-boiling
EF
-heat Δ KE
-move faster
-temp.
-gas
Boiling Gas
Phase Change Graph (T vs t)Phase Change Graph (T vs t)
A
BC
DE
F
AB
-KE
-slows down
-temp.
-Gas
BC
-PE
-closer together
-temp. stays same
-Condensation
CD
-KE
-slows down
-temp.
-Liquid
Phase Change Graph (T vs t)Phase Change Graph (T vs t)
Energy FlowEnergy Flow
• Endothermic Endothermic – A change that is caused by A change that is caused by absorbing energy from its absorbing energy from its surrounding.surrounding.
– Melting, vaporizing, sublimingMelting, vaporizing, subliming
• ExothermicExothermic– A change is caused by releasing A change is caused by releasing energy to the surroundings.energy to the surroundings.
– Freezing, condensing, depositingFreezing, condensing, depositing
What is the boiling point?
What is the melting point?
What is the freezing point?
Boiling
Boiling Point
MeltingMelting Point
FreezingFreezing Point &
Phase Change Graph (T vs Phase Change Graph (T vs t)t)