Chemical Reactions

By: Rebecca Carroll

Physical Change

A change affecting the form of a chemical substance but not it's chemical composition.

Note that all physical changes can be reversed.

Ex.

Color Change

Temperature Change

Breaking of an object

Chemical Change

A change affecting the chemical composition of an object. Chemical Changes form and/or break the bond between atoms.


Ex.

Oxidation

Burning of Wood

Digesting Food

Precipitate

When a substance previously mixed with another is separated from a solution.

Ex.

Mixing salt and water, then heating the solution to the point where the water evaporates and the salt is left.

Exothermic

When a reaction of substances is followed by the release of heat.

Ex.

When burning a candle, the flame releases heat.

Endothermic

When a reaction of substances is followed by the absorption of heat.

Ex.

When melting ice cubes and the ice must absorb the heat in order to melt.