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