## Q. 14.1

Explaining Acidity with the Arrhenius and Brønsted–Lowry Theories

Account for the acidic properties of nitrous acid ($HNO_2$) using the Arrhenius theory and the Brønsted–Lowry theory, and identify the conjugate base of $HNO_2$.

STRATEGY

To account for the acidity of a substance, consider how it can produce $H^+$ ions in water (Arrhenius theory) and how it can act as a proton donor (Brønsted–Lowry theory).

## Verified Solution

$HNO_2$ is an Arrhenius acid because it dissociates in water to produce $H^+$ ions:

$\mathrm{HNO}_2(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{NO}_2^{-}(a q)$

Nitrous acid is a Brønsted–Lowry acid because it acts as a proton donor when it dissociates, transferring a proton to water to give the hydronium ion, $H_3O^+$:

The conjugate base of $HNO_2$ is $NO_{2}^{-}$, the species that remains after $HNO_2$ has lost a proton