Question

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

Calcium nitrate solution and zinc nitrate solution.

Answer 1

• To distinguish between the two compounds that is calcium nitrate solution and zinc nitrate solution, we add ammonium hydroxide in excess to both the compounds.
• As a result of this one of the compounds will have an insoluble white precipitate.
• That compound will be calcium nitrate solution because calcium nitrate reacts with ammonium hydroxide to form calcium hydroxide (Ca(OH)₂ which is insoluble in excess ammonium hydroxide.
• Chemical reaction:

$$\begin{gathered} \mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{Ca}(\mathrm{OH}{)}_2\left(\mathrm{s}\right)\downarrow +2{\mathrm{NaNO}}_3(\mathrm{aq}) \\ \mathrm{White}\mathrm{ppt} \end{gathered}$$