Dissociation equilibria of ammonium bifluoride in water Ammonium bifluoride or ammonium hydrogen fluoride is a salt of a weak base and a weak acid.
The weak acid is because the second equilibria of $\ce{HF}$ written as:
$$\ce{HF + F- &lt;=&gt; HF2-}$$
and it has constant of $\pu{3.963 M}$.
But does the bifluoride anion further dissociate?
$\ce{HF}$ in water has many species: $\ce{H+},$ $\ce{F-},$ $\ce{HF2-},$ $\ce{H2F2}$ and $\ce{(HF)_nF-}.$ The $\ce{NH4HF2}$ has a more acidic $\mathrm{pH}$ than a solution of $\ce{NH4F}$.
You need to write out all the possible equilibria just like you do in the case of a multiprotic acid like Phosphoric acid. You will also need to have a pKa for every equation. The bifluoride ion will obviously dissociate in water