1. Heating Curve
Turk

2. Energy is absorbed
Energy is released

3. Potential Energy- stored energy
Kinetic Energy- energy having to do with motion

4. Heat of Fusion
amount of heat needed to be absorbed to convert a unit of mass of a substance from a solid to a liquid at its melting point
q= mHf
heat of fusion for water is 334 joules per gram.
Example: How many joules are required to melt 255 g of ice at 0 C at 1 atm?

5. Heat of Vaporization
amount of heat needed to be absorbed to convert a unit mass of a substance from its liquid phase to gas phase.
q = Hvm
heat of vaporization for water is 2260 joules per gram.
Example: How many joules of energy are required to vaporize 423 g of water at 100 C and 1 atm?

6. Heating Curve for Water
vaporization E
gas D
100
condensation C
liquid
melting
Temperature (oC)
Melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes.
Note: The temperature of a substance does not change during a phase change. B A
freezing
solid
Heat added
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 487

7. Heating Curve
Temperature of the ice (solid) is increasing; increase in temperature means an increase in kinetic energy.
At 0oC the ice begins to melt. During melting, the temperature stays the same; there is no change in kinetic energy. There is a change in potential energy; potential energy is increasing.
The temperature of the water now rises from 0oC to 100oC.

8. Heating Curve
4. At 100oC, the water boils (changes to gas). When the water boils, the temperature stays the same; no change in kinetic energy. There is a change in potential energy; potential energy increases. 5. After all the water boils, the temperature of the gas rises.