Question

how can you tell a Ca(NO3)2 solution from a Zn(NO3)2 solution?

Answer 1

Explanation:

1) $Ca(NO_3)_2$ solution

$Ca(NO_3)_2(aq)\rightarrow Ca^{2+}(aq}+NO_3^{1-}{aq}$

To the solution of calcium nitrate add few drops of sodium hydroxide. Formation of white solid calcium hydroxide will be observed.

$Ca(NO_3)_2(aq)+NaOH(aq)\rightarrow NaNO_3(aq)+ Ca(OH)_2(aq)(white)$

2) $Zn(NO_3)_2$ solution

$Zn(NO_3)_2(aq)\rightarrow Zn^{2+}(aq}+NO_3^{1-}{aq}$

To the solution of $Zn(NO_3)_2$ add few drops of liquid ammonia which will precipitate out white gelatinous zinc hydroxide from the solution. And this zinc hydroxide gets dissolves when excess of liquid ammonia is added to the solution.

${Zn^{2+}(aq)+2NH_3(aq)+2H_2O(l)\righarrow Zn(OH)_2(s)(\text{white precipitate})+2NH_4^{+}(aq)}$