STUDENT RESOURCE 7.1
acid a substance that tastes sour, conducts
pH a measure of the amount of acid in a
electricity, and reacts with many metals
Lemon juice is an acid. It tastes sour,
A low pH means a solution is acidic.
conducts electricity, and reacts with
Stomach acid has a pH of about 2.
certain metals, such as iron.
A high pH means a solution is basic.
Ammonia solution used for cleaning is a
base a substance that tastes bitter and
base and has a pH of about 11.
Soap is a base. It tastes bitter and
salt the product of a chemical reaction
between an acid and a base
When an acid combines with a
indicator a substance that changes color
base, a salt and water are produced.
with a change in pH
For example, when hydrochloric acid
Phenol red is an example of an
(stomach acid) and the base sodium
indicator. Phenol red is yellow in an acid,
hydroxide (lye) react, the products are
red in a base, and orange in a neutral
water and sodium chloride, table salt.
CHEMISTRY • SECTION 7 ACIDS AND BASES