Science Ch. 3 Lesson 2 By: Grace O’Doherty

Change of State change of state is the conversions of a substance from one state to another

Melting the change from a solid to a liquid melting point: the temp. the substance must reach in order to change from solid to liquid the melting point of a substance is a characteristic property because it will always be the same regardless of the quantity endothermic when a substance is being melted its molecules are overcoming their attraction to each other

Freezing the change from a liquid to a solid freezing point: the temp. that a liquid turns into a solid the freezing point of a substance is also a characteristic property freezing and melting occur at the same temp. (it just has to do with whether energy is being added or removed) exothermic

Vaporization the change from a liquid to a gas there are two types: boiling and evaporation

Boiling occurs throughout the entire liquid all substances have different boiling points endothermic

Evaporation only takes place at the liquids surface evaporation is also a characteristic property endothermic

Pressure Affects Boiling Points The higher you go the lower the pressure gets and because the pressure gets lower water boils at a lower temp.

Condensation The change from a gas to a liquid large numbers of atoms/molecules must clump together The atoms/molecules also slow down and get more attracted to eachother exothermic

Sublimation The change from a solid to a gas carbon dioxide in the solid state is called dry ice the attraction between all of the particles/molecules in a substance must be overcome the atoms/molecules must also move from being very tightly packed to being spread apart endothermic

Endothermic/Exother mic something is endothermic when energy is being taken in or absorbed something is exothermic when energy is being removed or taken out of

NOTE! the temp. of a substance remains constant until the entire substance has completely changed state

The End!