Question

The questions (i) to (v) refer to the following salt solutions listed A to F :
(A) Copper nitrate
(B) Iron (II) sulphate
(C) Iron (III) chloride
(D) Lead nitrate
(E) Magnesium sulphate
(F) Zinc chloride

(i) Which two solutions will give a white precipitate when treated with dilute hydrochloric acid followed by Barium chloride solution?
(ii) Which two solutions will give a white precipitate when treated with dilute nitric acid followed by silver nitrate solution?
(iii) Which solution will give a white precipitate when either of dilute hydrochloric acid or dilute sulphuric acid is added to it?
(iv) Which solution becomes deep blue in colour when excess of ammonium hydroxide is added to it?
(v) Which solution gives a white precipitate with an excess of ammonium hydroxide solution?

Answer 1

(i) Two solutions that gives a white precipitate when treated with dilute hydrochloric acid followed by barium chloride solution are:

(B) Iron (II) sulphate: In this reaction, a white precipitate, Barium sulphate will get formed.

$$\begin{gathered} {\mathrm{FeSO}}_4\left(\mathrm{s}\right)+{\mathrm{BaCl}}_2\left(\mathrm{s}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{s}\right)+{\mathrm{FeCl}}_2\left(\mathrm{s}\right) \\ \mathrm{Ppt} \end{gathered}$$

(E) Magnesium sulphate: In this reaction, the same white precipitate, Barium sulphate will get formed.

$$\begin{gathered} {\mathrm{MgSO}}_4\left(\mathrm{s}\right)+{\mathrm{BaCl}}_2\left(\mathrm{s}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{s}\right)+{\mathrm{MgCl}}_2\left(\mathrm{s}\right) \\ \mathrm{Ppt} \end{gathered}$$

(ii) Two solutions that will give a white precipitate when treated with dilute nitric acid followed by silver nitrate solution:

(C) Iron (III) chloride

(F) Zinc chloride

A white precipitate, Silver chloride will get formed in both the cases.

$$\begin{gathered} {\mathrm{FeCl}}_3\left(\mathrm{s}\right)+3{\mathrm{AgNO}}_3\left(\mathrm{s}\right)\to 3\mathrm{AgCl}\left(\mathrm{s}\right)+\mathrm{Fe}{\left({\mathrm{NO}}_3\right)}_3\left(\mathrm{s}\right) \\ \mathrm{Ppt} \\ {\mathrm{ZnCl}}_2\left(\mathrm{s}\right)+2{\mathrm{AgNO}}_3\left(\mathrm{s}\right)\to 2\mathrm{AgCl}\left(\mathrm{s}\right)+\mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right) \\ \mathrm{Ppt} \end{gathered}$$

(iii) Solution which will give a white precipitate when either dilute hydrochloric acid or dilute sulphuric acid is added to it:

(D) Lead nitrate: With dilute sulphuric acid, it forms Lead (II) sulphate as a precipitate.

$$\begin{gathered} \mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)\to {\mathrm{PbSO}}_4\left(\mathrm{s}\right)+2{\mathrm{HNO}}_3\left(\mathrm{l}\right) \\ \mathrm{Ppt} \end{gathered}$$

With dilute hydrochloric acid, it forms Lead (II) chloride as a precipitate.

$$\begin{gathered} \mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{l}\right)\to {\mathrm{PbCl}}_2\left(\mathrm{s}\right)+2{\mathrm{HNO}}_3\left(\mathrm{l}\right) \\ \mathrm{Ppt} \end{gathered}$$

(iv) Solution that becomes deep blue in colour when excess ammonium hydroxide is added to it:

(A) Copper nitrate

In this reaction, Copper (II) hydroxide is formed, which is deep blue in color.

$$\begin{gathered} \mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{l}\right)\to \mathrm{Cu}(\mathrm{OH}{)}_2\left(\mathrm{s}\right)+2{\mathrm{NH}}_4{\mathrm{NO}}_3(\mathrm{s}) \\ \mathrm{Blue} \end{gathered}$$

(v) Solution which gives a white precipitate with an excess of ammonium hydroxide solution:

(F) Zinc chloride

It forms a white precipitate, Zinc (II) hydroxide.

$$\begin{gathered} {\mathrm{ZnCl}}_2\left(\mathrm{s}\right)+2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{l}\right)\to \mathrm{Zn}(\mathrm{OH}{)}_2\left(\mathrm{s}\right)+2{\mathrm{NH}}_4\mathrm{Cl}(\mathrm{s}) \\ \mathrm{Ppt} \end{gathered}$$