# Question #e7848

Dec 6, 2017

$N {H}_{4}^{+}$ is the acid.
$O {H}^{-}$ is the base
$N {H}_{3}$ is the conjugate base
${H}_{2} O$ is the conjugate acid

#### Explanation:

The best way to figure out what's an acid or a base is to simply track the movement of your ${H}^{+}$ ions.

• The species that donates an ${H}^{+}$ ion is an $\textcolor{red}{\text{acid}}$.
• The species that recieves an ${H}^{+}$ ion is a $\textcolor{b l u e}{\text{base}}$.

Notice that the $N {H}_{4}^{+}$ ends up becoming $N {H}_{3}$, indicating the loss of one ${H}^{+}$ ion. Similarly, $O {H}^{-}$ becomes ${H}_{2} O$, indicating a gain of a ${H}^{+}$ ion.

So, you can say that $N {H}_{4}^{+}$ is the acid, and $O {H}^{-}$ is the base.

Conjugates are basically the "other" term. For every acid, you have a conjugate base (that no longer has that extra ${H}^{+}$ ion), and for every base, you have a conjugate acid (that has an extra ${H}^{+}$ ion).

As mentioned above, $N {H}_{4}^{+}$ ends up becoming $N {H}_{3}$ post deprotonation (donation of the ${H}^{+}$) ion, so $N {H}_{3}$ is your conjugate base. Similarly, $O {H}^{-}$ becomes ${H}_{2} O$ post protonation, so it is your conjugate acid.

Hope that helped :)