1. Heat Energy and Changes of State

2. Matter may exist as a solid, liquid, or a gas.

3. Changes of State An increase or decrease in energy and temperature of matter can cause the matter to go from one state to another. Melting: solid changes to a liquid

4. Changes of State Solidification: liquid changes to a solid

5. Changes of State Evaporation: liquid changes to a gas

6. Changes of State Condensation: gas changes to a liquid

7. Changes of State Sublimation: – Solid to a gas – Gas to a solid

8. As seen in the side- by-side images above, water ice in a trench on Mars is sublimating in the cold, thin air over the course of four Martian days (sols).

9. These images show the Martian north pole throughout changing seasons on Mars. Increased warming as spring progresses in the northern hemisphere has sublimated the carbon dioxide ice and frost below 70 degrees north latitude.

10. Frost occurs when water vapor in the air changes directly into a solid.

11. Stored Heat and Changes in State The temperature remains constant while water is changing state. – The heat being added during a phase change is being changed into stored heat