The document discusses the three states of matter - solid, liquid, and gas - and the changes between them due to heat. It explains phase changes like melting, freezing, evaporation, boiling, and condensation. Melting and freezing occur at specific temperatures called melting and freezing points. Evaporation turns liquid to gas, while condensation turns gas back to liquid. Boiling is evaporation from within the liquid. Pressure affects boiling point by controlling evaporation. Refrigeration uses evaporation and condensation of gases to transfer heat.

1. 8 th Grade Chapter 5 Lesson 4 Pgs. 206-218 For Student Use Only

2. Heat and Phase Change Three States of Matter: Solid Liquid Gas Changes due to a loss or gain of heat

3. Heat and Phase Change Solids to Liquids= melting This point is called the melting point Liquid to Solid= freezing This point is called the freezing point Freezing point is affected by solutes

4. Heat and Phase Change Latent Heat Solid to liquid produces no temperature change This is called latent heat Heat of fusion Heat required to turn a certain amount of solid into a liquid without changing temperature

5. Heat and Phase Change Evaporation and Condensation Evaporation- liquid to a gas Factors that affect evaporation Higher temperatures Greater surface area Air speed over a liquid

6. Heat and Phase Change Evaporation Liquids that evaporate quickly are volitile Liquids that evaporate slowly are involitile

7. Heat and Phase Change Internal Evaporation Evaporation that takes place in the liquid as opposed to the usual surface Requires high heat This is also called boiling When evaporation is throughout the liquid Boiling Point- when boiling takes place

8. Heat and Phase Change Boiling: Evaporation will not occur any quicker above 100 degrees Pressure: Affects the boiling point Control the pressure and control the boiling point

9. Heat and Phase Change Pressure Cooker: Uses pressure to make food cook faster Heat of Vaporization: Heat required to change a given amount of liquid into a gas without raising the temperature

10. Heat and Phase Change Condensation: Gas changing into a liquid This happens when warm things get cold Saturation Point When amount of water evaporating equals the amount of condensing

11. Heat and Phase Change Evaporation and Condensation Heat flows from higher to lower concentration Refrigeration is using heat and condensation

12. Heat and Phase Change Principles of Refrigeration: When a gas is compressed its temperature rises When a gas is allowed to expand its temperature falls When a liquid evaporates it absorbs heat from the surroundings When a gas condenses is releases heat into its surroundings

13. Heat and Phase Change Sublimation: A gas changing directly into a solid 4 th State of Matter: Plasma- super heated gas