Physical and Chemical Changes: Definitions and Examples

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Physical and Chemical Changes

Physical Change

A physical change is a type of change in which the form of matter is altered, but the composition of the substance remains unchanged and no new substances are produced. The process of a physical change is generally reversible.

Physical changes include changes in size, shape, or state of a substance, which also includes dissolving.

Physical changes include all phase changes including:

Liquid to solid - Freezing

Solid to liquid - Melting

Liquid to gas - Evaporation

Gas to liquid - Condensation

Solid to gas - Sublimation

Gas to solid - Deposition

The following examples are examples of physical changes due to the fact that no new substances are produced, and that they are generally reversible.

Casting silver in a mold

Boiling water

Making ice cubes

Dissolving salt in water

Folding a shirt

Getting a haircut

Chemical Change

A chemical change is a process where one or more substances are altered into one or more new and different substances. The process of a chemical change is irreversible.

Some good indicators of a chemical change include changes in colour, odour, temperature, formation of bubbles (gas), formation of a new solid (precipitate), or the production of light.

The following examples are examples of chemical changes due to the fact that a new substance is produced and that the process is irreversible.

Tarnishing of silver

Baking a cake

Milk going sour