Date post: | 04-Jan-2016 |
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Topic: Chemistry
Aim: Explain the different types of phase changes and the energy changes involved.
Do Now: ON NOTES SHEET
HW: Ditto – Periodic Tables Families Review (last page of Periodic Table Notes Packet)
http://www.youtube.com/watch?v=XaDxwe8l3us&feature=related
Phase Changes
• Involves the absorption OR release of heat (energy).
Substance absorbs heat energy
Melting • Solid liquid
• Solid ABSORBS heat energy
Substance absorbs heat energy
Melting points of different substances• Iron: 1536ºC• Gold: 1063ºC• Glucose: 150ºC• Urea: 132-134ºC
Vaporization • Liquid gas
• Liquid ABSORBS heat energy
• When it occurs on surface of liquid: evaporation
LIQUID
GASLiquid absorbs heat energy
Boiling points of different substances• Alcohol (Ethanol): 79ºC• Iodine: 184.3ºC• Mercury: 356.9ºC• Olive oil: 300ºC• Jet fuel: 163ºC
Condensation • Gas liquid
• Gas LOSES heat energy
LIQUID
GASGas loses heat energy
Freezing • Liquid solid
• Liquid LOSES heat energy
Substance loses heat energy
Sublimation • Solid Gas
• No liquid phase
• Ex: dry ice
Solid
GASSolid absorbs 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.
And an animation of the phase changes of water
Let’s summarize…
1. List the different types of phase changes.
2. Explain what happens to heat energy in each phase change.
1. When a liquid becomes a solid, energy
1. does not change
2. is released
3. is absorbed
4. is first absorbed, then released
2. _______ is the process in which liquid changes to gas below the boiling point.
1. Sublimation
2. Condensation
3. Evaporation
4. Combustion
3. On a hot day, the outside of a glass containing a cold drink becomes frosty. When touching the glass, it feels
1. water that has passed through the glass
2. water that has condensed from a gas in the air
3. water that has solidified
4. water that has absorbed energy
4. The change of a liquid to a solid is called
1. freezing
2. Melting
3. sublimation
4. vaporization
5. During which of the following processes is there a decrease in the heat content of the form of water indicated?
1. Ice as it forms on a lake
2. Water droplets as they fall to the ground
3. Water as it evaporates from a pond
4. Snow as it melts on a mountainside
6. When substances go directly from the solid phase to the gas phase, the phase change is called
1. sublimation
2. condensation
3. evaporation
4. vaporization
Heat (thermal energy)
Tem
pera
ture
º C
.
100
0
A
B
C
DE
melting
freezing
condensing
boiling
• http://www.youtube.com/watch?v=vDZhUkp30tE&feature=related