3.3 Notes
- 1. Phase Changes A reversible physical change that occurs when a substance changes its state, solid, liquid or gas Melting, Freezing, vaporization, condensation, sublimation, and deposition are six common phase changes
- 2. Temperature and phase changes The temperature of a substance does not change during a phase change. Freezing and melting points are the same temperature Vaporization and Condensation points are the same
- 3. Energy and Phase Change Energy is either absorbed or released during a phase change Endothermic change absorbs energy (Melting) Exothermic change releases energy into surroundings (freezing) Heat of fusion is the amount of energy something absorbs in order to melt
- 4. Melting and Freezing The arrangement of molecules become more orderly as a substance freezes (becomes solid), and less orderly as something melts (becomes liquid).
- 5. Vaporization and Condensation Vaporization is an endothermic phase change of a liquid to a gas The amount of energy it takes to cause a substance to go from a solid to a liquid is called the heat of vaporization
- 6. Two types of Vaporization Evaporation- Takes place at the surface of a liquid (occurs below boiling). Vapor pressure is caused by the collision of particles with the walls of a container Boiling- when vapor pressure becomes equal to the atmospheric pressure substances boil
- 7. Condensation Condensation is when a substance turns from a gas to liquid. EX. include dew, water on the outside of a glass of lemonade on a hot day.
- 8. Sublimation and Deposition Sublimation is a phase change in which a solid goes directly to a gas (Dry Ice) Deposition is a phase change in which a gas becomes a solid (Frost)