Question

State the observation you would make on adding ammonium hydroxide to an aqueous solution of ferrous sulfate.

Answer 1

Double displacement reaction:

Those reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions.

For Example:${\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+6\mathrm{HCl}\left(\mathrm{aq}\right)\to 2{\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Explanation:

Adding an aqueous solution of ferrous sulfate$\left({\mathrm{FeSO}}_4\right)$ to ammonium hydroxide$\left({\mathrm{NH}}_4\mathrm{OH}\right)$ would lead to the formation of ferrous hydroxide$\mathrm{Fe}{\left(\mathrm{OH}\right)}_2$ (green precipitates) by a double displacement reaction.

Reaction involved:

${\mathrm{FeSO}}_4\left(\mathrm{aq}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\hspace{0.17em}\to \underset{(\mathrm{Green}\mathrm{ppt})}{\mathrm{Fe}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)}+{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)$

Therefore, green-colored precipitates of Ferrous Hydroxide are observed.