Question

Give the balanced equations for reactions of aqueous ammonia with the following:
Zinc sulphate

Answer 1

Reaction with zinc sulphate $\left({\mathrm{ZnSO}}_4\right)$:

• When ammonium hydroxide $\left({\mathrm{NH}}_4\mathrm{OH}\right)$ is treated with zinc sulphate solution, it forms a white gelatinous precipitate of $\mathrm{Zn}(\mathrm{OH}{)}_2$, which is soluble in excess of ammonium hydroxide.
• One mole of zinc sulphate reacts with two moles of ammonium hydroxide to form one mole of $\mathrm{Zn}(\mathrm{OH}{)}_2$ and one mole of ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4$.

The balanced equation is:

${\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)⟶\mathrm{Zn}(\mathrm{OH}{)}_2\left(\mathrm{s}\right)+{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4(\mathrm{aq})$