Changes of State Chapter 3 Section 2

Change of State Change of a substance from one physical form to another All physical changes Energy changes when change of state occurs –Either add or remove energy

Changes of State 1.Melting and melting point (liquid) 2.Freezing and freezing point (solid) 3.Vaporization- boiling and evaporation, boiling point (gas) 4.Condensation 5.Sublimation – solid to a gas (no liquid state)

4 States of Matter Solid – specific volume and shape Liquid - definite volume but not shape Gas - does not have a definite volume or shape Plasma - starts as a gas and then becomes ionized; it consists of free-moving ions and electrons, it takes on an electric charge, its different from those of a solid, liquid, or gas Examples: stars, nebulas, northern lights, neon signs and lights

Melting Solid to liquid Energy must be added –Endothermic because energy is gained Melting Point  temperature at which a substance changes from a solid to a liquid

Freezing Liquid to a solid Energy is removed – exothermic change Freezing point  temperature at which a substances freezes

Vaporization Liquid to gas 2 types: –Boiling  vaporization takes place throughout liquid Boiling point- temperature at which liquid boils –Evaporation  vaporization that occurs at the surface of a liquid below boiling point EXAMPLE: sweat

Condensation Gas to liquid Condensation point of a substance is the same temperature as its boiling point at a given pressure Exothermic change - energy is removed (EXITS)

Sublimation Solid to a gas Endothermic change- gain energy (ENters) EXAMPLE: dry ice