Strong acids and bases are those that ionize completely in solution. In contrast, weak acids and bases ionize only partially in solution.

, hydrogen fluoride, is an example of a very strong acid. In solution, it dissolves completely to form  and . 

, sodium hydroxide, is an example of a very strong base. In solution, it dissolves completely to form  and .

, acetic acid, is an example of a weak acid. In solution, it dissolves partially to form  and .

, ammonia, is an example of a weak base. In solution, it accepts a proton to form  and .

Using the concentration of  as a conversion factor, we can convert the volume of  to moles by dimensional analysis:

At the equivalence point of the titration:

Acid dissociation constant which is denoted as  is the equilibrium constant for the ionization of an acid. Therefore, the numerator contains the product of the concentrations of the substances on the product side of the chemical equation. The denominator contains the product of the concentrations of the substances on the reactant side of the chemical equation.   is omitted in the acid dissociation constant expression because as the solvent it is in excess and therefore the change in its concentration is negligible in comparison to the other substances in solution.

Recall that a Bronsted-Lowry acid donates a proton. From the equation, we can see that  becomes , which it lost an , or a proton. Thus, water must be the Bronsted-Lowry acid.

Recall that a Lewis base accepts a proton, while a Lewis acid donates a proton. Looking at the equation, we can see that  becomes . Since  accepted a proton, it must be the Lewis base.

There are three main definitions for acids and bases: the Lewis acids and bases, Bronsted-Lowry acids and bases, and Arrhenius acids and bases.

A Lewis acid is a species which can accept an electron pair from a donor. An example of a Lewis acid is ; as a cation, it can accept an electron pair. A Lewis base is a species which can donate an electron pair. An example of a Lewis base is ; as an anion, it can donate an electron pair.

A Bronsted-Lowry acid is a species which can donate a proton. An example of a Bronsted-Lowry acid is , which can donate its hydrogen ion. A Bronsted-Lowry base is a species which can accept a proton from a donor. An example of a Bronsted-Lowry base is , which can accept a hydrogen ion in order to become water.

An Arrhenius acid is a species which releases hydrogen ions into solution. An example of an Arrhenius acid is . When this compound dissolves in aqueous solution, it produces  and . An Arrhenius base is a species which releases hydroxide ions into solution. An example of an Arrhenius base is . When this compound dissolves in aqueous solution, it produces  and .

PH is defined as , where  is hydronium concentration). In order to do this we simply take :

=

Remember a Brønsted-Lowry acid is defined as a proton donor.

In the forward reaction,  is a proton donor. In the backward reaction,  is the proton donor.

The acids in this reaction are  and .