A reaction between an acid and a base is called a neutralization reaction. This type of reaction occurs when the hydrogen ions from the acid and the hydroxide ions from the base combine to form water. The products of a neutralization reaction are always a salt and water.

For example, when hydrochloric acid (HCl) and sodium hydroxide (NaOH) are mixed, the following reaction occurs:

HCl + NaOH → NaCl + H2O

The products of this reaction are sodium chloride (NaCl) and water (H2O).