Question

Dilute sulphuric acid produces white precipitate when added to the solution of:
A.Copper nitrate
B.Zinc nitrate
C.Lead nitrate
D.Sodium nitrate

Answer 1

The reaction of dilute sulphuric acid with copper nitrate, zinc nitrate, lead nitrate and sodium nitrate is a double decomposition reaction. The solubility rule for sulphates states that almost all the sulphates are soluble except those of ${\text{B}}{{\text{a}}^{2 + }}$, ${\text{P}}{{\text{b}}^{2 + }}$, ${\text{C}}{{\text{a}}^{2 + }}$ and ${\text{S}}{{\text{r}}^{2 + }}$.

Complete step by step answer:
When dilute sulphuric acid reacts with copper nitrate a double decomposition reaction occurs. In the reaction, copper sulphate and nitric acid are produced.
Thus, the reaction is as follows:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + Cu}}{\left( {{\text{N}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}\left( {{\text{aq}}} \right){\text{ }} \to {\text{ CuS}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + 2HN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}} \right)$
According to the solubility rule for sulphates, copper sulphate is soluble in water and does not precipitate out.
Thus, dilute sulphuric acid does not produce white precipitate when added to the solution of copper nitrate.
When dilute sulphuric acid reacts with zinc nitrate a double decomposition reaction occurs. In the reaction, zinc sulphate and nitric acid are produced.
Thus, the reaction is as follows:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + Zn}}{\left( {{\text{N}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}\left( {{\text{aq}}} \right){\text{ }} \to {\text{ ZnS}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + 2HN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}} \right)$
According to the solubility rule for sulphates, zinc sulphate is soluble in water and does not precipitate out.
Thus, dilute sulphuric acid does not produce white precipitate when added to the solution of zinc nitrate.
When dilute sulphuric acid reacts with lead nitrate a double decomposition reaction occurs. In the reaction, lead sulphate and nitric acid are produced.
Thus, the reaction is as follows:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + Pb}}{\left( {{\text{N}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}\left( {{\text{aq}}} \right){\text{ }} \to {\text{ PbS}}{{\text{O}}_{\text{4}}}\left( {\text{s}} \right){\text{ + 2HN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}} \right)$
According to the solubility rule for sulphates, lead sulphate is not soluble in water and thus, lead sulphate precipitates out.
Thus, dilute sulphuric acid produces white precipitate when added to the solution of lead nitrate.
When dilute sulphuric acid reacts with sodium nitrate a double decomposition reaction occurs. In the reaction, sodium sulphate and nitric acid are produced.
Thus, the reaction is as follows:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + 2NaN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}} \right){\text{ }} \to {\text{ N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_{\text{4}}}\left( {{\text{aq}}} \right){\text{ + 2HN}}{{\text{O}}_{\text{3}}}\left( {{\text{aq}}} \right)$
According to the solubility rule for sulphates, sodium sulphate is soluble in water and does not precipitate out.
Thus, dilute sulphuric acid does not produce white precipitate when added to the solution of sodium nitrate.
Thus, dilute sulphuric acid produces white precipitate when added to the solution of lead nitrate.

Thus, the correct option is option (C).

Note: A reaction in which two reactants interchange the cations and anions and produce two new compounds is known as a double decomposition reaction. Thus, the reaction of dilute sulphuric acid with copper nitrate, zinc nitrate, lead nitrate and sodium nitrate is a double decomposition reaction.