Question

Name a hydroxide which is soluble in excess of ammonium hydroxide.

Answer 1

• A hydroxide which is soluble in excess ammonium hydroxide is Zinc hydroxide, $\mathrm{Zn}(\mathrm{OH}{)}_2$.
• The precipitate of zinc hydroxide formed at some point of a reaction does not dissolve in excess of ammonium hydroxide.
• Chemical reaction:

$$\begin{gathered} \mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2\left(s\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(l\right)\to \mathrm{Zn}(\mathrm{OH}{)}_2\left(s\right)+2{\mathrm{NH}}_4\left({\mathrm{NO}}_3\right)(s) \\ \mathrm{Precipitate} \end{gathered}$$