1. 0 1 2 3 4 5 Thermal Energy (Heat) 150 100 50 0 Temperature (°C) Notes: Thermal Energy and Phase Changes

2. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Adding Thermal Energy to H 2 0 Ice

3. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Adding Thermal Energy to H 2 0 Melting Ice

4. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Adding Thermal Energy to H 2 0 Melting Ice Water

5. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Adding Thermal Energy to H 2 0 Melting Ice Water Vaporization

6. Adding Thermal Energy to H 2 0 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Melting Ice Water Vapor Vaporization

7. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Taking Thermal Energy from H 2 0 Vapor

8. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Taking Thermal Energy from H 2 0 Vapor Condensation

9. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Taking Thermal Energy from H 2 0 Water Vapor Condensation

10. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Taking Thermal Energy from H 2 0 Freezing Water Vapor Condensation

11. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Taking Thermal Energy from H 2 0 Freezing Ice Water Vapor Condensation

12. 0 1 2 3 4 5 Thermal Energy 150 100 50 0 Temperature (°C) Thermal Energy and Phase Changes Freezing Liquid Gas Condensation Melting Solid Vaporization

13. Rules of Thumb 1) Horizontal lines are phase changes 2) Diagonal lines are changes in temperature 3) Adding heat causes different phase changes than removing it!

14. VAPORIZATION (Liquid-Gas) evaporation – a change in phase from liquid to gas at the surface. – this cools the remaining liquid! boiling – a change in phase from liquid to gas below the surface. – this cools the remaining liquid! boiling point – the temperature that an object vaporizes or condenses.

15. Condensation (Gas  Liquid) this is a warming process for the liquid. gas molecules strike surface of liquid and give up so much energy that they can’t stay in gaseous phase examples droplets forming on mirror droplets on glass of water

16. Phase Change Process (S & L) melting – thermal energy is used to break bonds – the bonds that hold molecules in vibrating lattice structure are breaking. – the intermolecular forces lessen freezing – thermal energy is used to create bonds and hold molecules in place – the bonds that will hold molecules in position are forming – the intermolecular forces increase – melting point – the temperature at which an object either melts or freezes.