Solids, Liquids, & Gases Changes of State Chapter 2 Section 2

Physical Change Alters the form of a substance, but does not change it to another substance Tearing paper Bending a nail

Chemical Change When a substance is changed into a different substance with different properties Burning wood Rusting metal

Thermal Energy Energy from the movement of its particles

Chemical Energy Energy from the chemical bonds within matter

Law of Conservation of Energy Energy can change forms, but can not be created or destroyed

Liquid  Solid Melting –Solid  Liquid Freezing –Liquid  Solid

Vaporization (L  G) Evaporation –Vaporization that takes place at the surface of the liquid Boiling –Vaporization that takes place throughout the liquid

Condensation (G  L) Gas molecules lose enough energy to become liquid

Boiling Point & Air Pressure Boiling point decreases as Air Pressure decreases Water boiling temp –Sea Level 100 o C –Lafayette (5000+ ft.) 94 o C

Sublimation (S  G) When solid molecules gain enough energy to turn directly into a gas –Dry Ice Frozen CO 2

Chemical Reactions When 1 or more chemicals change to form a new chemical