1. Phase Changes in Water AIM: How does the Atmosphere store energy?

2. Water exists on Earth in three states: solid (ice), liquid, and gas (water vapor) These “states of matter” can also be called “phases of matter” How do temperatures on our planet allow us to experience all three states of matter?

3. The Water Cycle!

4. When water changes from one phase to another, a great deal of energy is involved

5. Energy gained – melt and vaporize Energy released – condense and freeze

6. Notice temperature does not increase or decrease during a phase change.

7. We call this latent heat = hidden energy that is absorbed or released when matter changes state A type of potential energy required to rearrange molecules only – not change temperature. A type of potential energy required to rearrange molecules only – not change temperature. Animation

9. How do we measure energy? Scientists use joules (J) to measure energy Named for the scientist who discovered that heat is a form of energy ***Notice – more energy to boil (vaporize) and condense than to melt or freeze James Prescott Joule

10. Specific Heat Different substances absorb different amounts of energy as their temperatures change…WHY? The reason is because they have different specific heats = the energy needed to raise the temperature of 1 gram of a substance 1  C, without changing its state

11. The higher the specific heat of a substance, the more energy needed to raise its temperature

12. For example, it takes about 33 times as much energy to heat 1 g of water at 1  C than it takes to hear 1 g of lead at 1  C (the same amount of substance at the same temperature)