When water
dissociates, it breaks apart into an equal number of
hydrogen ions and
hydroxide ions. In contrast, when other substances dissociate, they may
release more hydrogen ions or more hydroxide ions. For example,
hydrochloric acid releases more hydrogen ions as it dissociates, and
sodium hydroxide releases more hydroxide ions.
Depending on its
concentration of hydrogen ions versus hydroxide ions, a substance can be classified as either an
acid or a
base.
The
pH scale measures how
acidic or how
basic a substance is. It ranges from
0 to
14, with
7 being
neutral.
When a substance has a
pH of 7, like water does, it releases an equal
concentration of
hydrogen and
hydroxide ions.
When a substance has a
pH of greater than 7, it’s classified as a
base and releases a greater concentration of
hydroxide ions.The more hydroxide ions that are released, the more
basic the substance is. Bases tend to feel slippery and are often used as household cleaners. Milk of magnesia and
ammonia are both
common bases.
When a substance has a
pH of
less than 7, it’s classified as an
acid and releases a greater concentration of hydrogen ions.
The more hydrogen ions that are released,
the more acidic the substance. Acids tend to taste sour. Lemon juice, stomach acid, and coffee are all examples of acids.
