Question

Give a chemical test to distinguish between the following pair of compounds

Calcium nitrate solution and zinc nitrate solution

Answer 1

Reagent	Calcium nitrate solution	Zinc nitrate solution
Ammonium hydroxide	When calcium nitrate react with ammonium hydroxide, a white precipitate of calcium hydroxide is formed. $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\to \underset{\mathrm{white}\mathrm{precipitate}}{\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)}+2{\mathrm{NH}}_4{\mathrm{NO}}_3\left(\mathrm{aq}\right)$	When zinc nitrate react with ammonium hydroxide, a white precipitate of zinc hydroxide is formed. $\mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{aq}\right)\to \underset{\mathrm{white}\mathrm{precipitate}}{\mathrm{Zn}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)}+2{\mathrm{NH}}_4{\mathrm{NO}}_3\left(\mathrm{aq}\right)$
Excess reagent is added	Calcium hydroxide does not dissolves in excess reagent	Zinc hydroxide dissolves in excess reagent $\mathrm{Zn}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)+4{\mathrm{NH}}_3\left(\mathrm{aq}\right)\to \underset{\mathrm{ammine}\mathrm{complex}}{\left[\mathrm{Zn}{\left({\mathrm{NH}}_3\right)}_4\right]{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)}$