1. Important Terms & Notes Feb. 27-28, 2014

2. Energy Flow During Phase Changes of Matter Energy must be ABSORBED by matter when the phase changes from: – Solid to Liquid and Liquid to Vapor. Energy must be RELEASED by matter when the phase changes from: – Vapor to Liquid and Liquid to Solid.

3. Heat of Vaporization The amount of heat required to change the phase of 1 gram of a substance in liquid form into 1 gram of vapor. Q = mL For H 2 0: L = 540 cal/g

4. Heat of Fusion The amount of heat given up to change the phase of 1 gram of a substance in liquid form into 1 gram of solid form (crystal/ice). Q = mL For H20: L = 80 cal/g

5. Heat Diagram of H 2 O

8. Phase Change Diagram of H 2 O

9. Questions Regarding the Phase Diagram 1. The phase of water present along "Leg A" of the diagram is: – ? vapor – ? solid – ? Liquid 2. The phase change taking place, in the right-to- left direction, along Leg "B" is: – ? melting – ? boiling – ? freezing

10. Questions Regarding the Phase Diagram 3. According to the diagram, during a phase change the temperature: – ? increases – ? remains constant – ? Fluctuates – ? decreases 4. At normal atmospheric pressure, water boils at: – ? 100 ºC – ? 0 ºC – ? -20 ºC – ? 120 º C

11. Questions Regarding the Phase Diagram 5. The phase of water present along "Leg E" of the diagram is: – ? solid – ? vapor – ? liquid 6. According to the diagram, freezing requires – ? absorption of energy – ? no energy change – ? removal of energy

12. The Refrigeration Cycle

13. Energy Interchange in a Refrigerator’s Cooling Cycle Heat is taken in from the inner compartment as the Refrigerant (liquid) evaporates in the pipes (Evaporator) and changes phase to vapor. The vapor is compressed and then pumped through a heat exchanger pipe assembly (Condenser) where heat is given up to the outside environment allowing the vapor to condense into liquid.