pH is the measure of the acidity or basicity of a solution. Acidity and basicity influence the properties of a solution. pH is measured with a system of measurement called the pH scale. A substance that has a pH of 7 is considered neutral -- equally acidic and basic. Substances with a pH greater than 7 are considered basic. Substances with a pH less than 7 are considered acidic.
The characteristics of acids and bases:
Acids increase the H+ ion concentration in a solution.
Acids neutralize bases.
Bases increase the OH- ion concentration in a solution.
Bases neutralize acids.
Ammonia is a base because it has a pH of 12
Orange juice is an acid because it has a pH of 3