Cracking the SAT Chemistry Subject Test

ACIDS AND BASES

Over the years, several different definitions for acids and bases have been
introduced.

For example:

Arrhenius: Acids    produce H

+   in  aqueous solution.

Bases   produce OH− in  aqueous solution.

Lewis: Acids    are electron    pair    acceptors   in  solution.Bases  are electron    pair    donors  in  solution.

Brønsted-Lowry:Acids    are proton  donors; bases   are proton  acceptors.

The Brønsted-Lowry definition is the one that’s most widely used today,
although it is commonplace for chemists to flip between the Brønsted-Lowry
and Arrhenius definitions.

Brønsted-Lowry Acids and Bases

The most important thing to remember about the Brønsted-Lowry definition of
acids and bases is that acids are proton donors and bases are proton acceptors.
The term proton is used to mean H+(aq), and H+(aq) reacts with water to form
the hydronium ion, H 3 O+(aq).

    Acid    Dissociation Reaction   of  a   Base

HA(aq)  →   H+(aq)  +   A−(aq   )   A−(aq)  +   H+(aq)  →   HA(aq)

or      or

HA(aq)  +   H 2 O(l)    →   H 3 O+(aq)  +   A

−(aq    )

    A−(aq)  +   H 2 O(l)    →   HA(aq)  +   OH

−(aq)