# How do you identify Bronsted-Lowry acids and bases?

Apr 20, 2016

Acids drop protons (${H}^{+}$), and bases pick them up.

#### Explanation:

Bronsted-Lowry theory states that an acid is a molecule that drops ${H}^{+}$ ions (protons), and a base picks them up again.

For example, in the reaction

$H C l + {H}_{2} O \to C {l}^{-} + {H}_{3} {O}^{+}$

the hydrochloric acid drops the hydrogen proton, while water picks it up. This means $H C l$ acts as an acid and ${H}_{2} O$ acts as a base.

After the reaction you then have a $C {l}^{-}$ ion which can pick up protons, so this is known as a conjugate base, and ${H}_{3} {O}^{+}$ has a new propensity to drop protons, and so is a conjugate acid.