change of phase fall 2010
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TRANSCRIPT
Agenda Bell work
• Notes: Change of Phase
• States of Matter Phet Simulation
• Pass in Lab Reports
• Define Specific Heat Capacity
• Distinguish between High and Low Specific Heat.
• Give an example of each
• How does water’s Specific heat control earth’s climate
• What is special about Islands and Peninsula's?
Change of PhaseChange of Phase
March 14, 2013March 14, 2013
ObjectivesObjectives
1.1. Explain changes in phase according to Explain changes in phase according to heat and energyheat and energy
2.2. Define each of the phase changesDefine each of the phase changes
Heat TransferHeat Transfer
When matter changes phase, a transfer of When matter changes phase, a transfer of thermal energy is involvedthermal energy is involved
EvaporationEvaporation
Liquid changes to gasLiquid changes to gas
Molecules that gainMolecules that gain
kinetic energy at the surface kinetic energy at the surface
get bumped free get bumped free
Becomes gas phase above Becomes gas phase above the liquidthe liquid
EvaporationEvaporation
Molecules that leave the liquid have the Molecules that leave the liquid have the most energy most energy
Energy of the liquid decreasesEnergy of the liquid decreases
Temperature of the liquid goes downTemperature of the liquid goes down
EX. PerspirationEX. Perspiration
Would evaporation be a cooling process if Would evaporation be a cooling process if there were no transfer of molecular energy there were no transfer of molecular energy from water to the air above?from water to the air above?
BoilingBoiling
Evaporation occurring within a liquid as Evaporation occurring within a liquid as well as its surfacewell as its surface
Bubbles of vapor form Bubbles of vapor form in the liquid and are in the liquid and are buoyed to the surface, buoyed to the surface, where they escapewhere they escape
Boiling like evaporation is a cooling Boiling like evaporation is a cooling processprocess
Boiling water is in thermal equilibriumBoiling water is in thermal equilibrium
It is being cooled by It is being cooled by boiling as fast as it boiling as fast as it is being heated by is being heated by energy from the energy from the heat sourceheat source
Since boiling is a cooling process, would it Since boiling is a cooling process, would it be a good idea to cool your hot, sticky be a good idea to cool your hot, sticky hands by dipping them into boiling water?hands by dipping them into boiling water?
CondensationCondensation
Gas to a LiquidGas to a Liquid
High energy molecules close to the surface High energy molecules close to the surface become attracted to the liquidbecome attracted to the liquid
Hit the surface with increased kinetic energyHit the surface with increased kinetic energy
Raising the temperature of the waterRaising the temperature of the water
Gas has a lot of energy to give upGas has a lot of energy to give up
If the water level in a dish of water remains If the water level in a dish of water remains unchanged from one day to the next, can unchanged from one day to the next, can you conclude that no evaporation or you conclude that no evaporation or condensation is taking place?condensation is taking place?
Melting and FreezingMelting and Freezing
Melting - solid to a liquidMelting - solid to a liquid
heat is absorbed the molecules vibrate heat is absorbed the molecules vibrate more and more breaking the attractive more and more breaking the attractive forcesforces
Freezing - liquid to a solidFreezing - liquid to a solid
energy is taken from the liquid, molecular energy is taken from the liquid, molecular motion slows down motion slows down
attractive forces between attractive forces between them bind them togetherthem bind them together
SublimationSublimation
Molecules jump directly from solid phase Molecules jump directly from solid phase to gaseous phaseto gaseous phase
Snow and ice melting on a hot sunny daySnow and ice melting on a hot sunny day
Dry ice in airDry ice in air
DepositionDeposition Molecules jump directly from gas phase to Molecules jump directly from gas phase to
solid phasesolid phase
Snow forming Snow forming high in the high in the atmosphereatmosphere