1. Heating and Cooling Curve

2. Heating Curve Is a graph of heat added versus temperature Is useful in describing the change in temperature and the amount of heat in a substance as it undergoes a phase change. See Figure 20.3 for the heating curve for ice ice at -25 0 C to steam at 125 0 C

3. Fig 20.3 Heating curve for water 125 F. 100 D.. E 75 50 25 0 B.. C -25. A

4. Fig 20.3 Heating curve for water 125 F. 100 D. E. 75 50 25 0 B.. C Line AB represents -25 A. ice the heating of ice

5. Fig 20.3 Heating curve for water 125 F. 100 D. E. 75 50 25 Melting Line BC  ice& liquid 0 B.. C  represents melting -25 of the ice

6. Fig 20.3 Heating curve for water 125 F. 100 D. E. 75 50 Liquid water Line CD represents 25 additional heat 0 B.. C increases temperature -25. A at 100 0 C

7. Fig 20.3 Heating curve for water 125 F. 100 D. E. 75 Liquid to gas line DE represents 50 The boiling of water at 25 100 0 C 0 B.. C -25 A.

8. Fig 20.3 Heating curve for water 125 F. 100 D. E. Water vapor 75 50 25 0 B.. C -25 A.

9. Cooling Curve Describes the change in temperature and the amount of heat during the cooling process The slope of the curve is decreasing when heat is removed from the material

10. Fig 20.4 Cooling Curve of water 1 2 3 4 5 100 Liquid 75 Gas 50 Gas-liquid 25 Liquid-solid solid 0 H o Vap -25 H o fus Stage1:Gaseous water cools. Stage 2: Gaseous water condenses Stage3: Liquid water cools. Stage4: Liquid water freezes Stage5: solid water cools