Question

The procedures and principles of qualitative analysis are covered in many introductory chemistry laboratory courses. In qualitative analysis, students learn to analyze mixtures of the common positive and negative ions, separating and confirming the presence of the particular ions in the mixture. One of the first steps in such an analysis is to treat the mixture with hydrochloric acid, which precipitates and removes silver ion, lead(II) ion, and mercury(I) ion from the aqueous mixture as the insoluble chloride salts. Write balanced net ionic equations for the precipitation reactions of these three cations with chloride ion.

Short answer

The balanced net ionic equations for the precipitation reactions of the three cations with chloride ion are as follows: 1. Silver ion: \(Ag^+ + Cl^- ⟶ AgCl\) 2. Lead(II) ion: \(Pb^{2+} + 2Cl^- ⟶ PbCl_2\) 3. Mercury(I) ion: \(Hg_2^{2+} + 2Cl^- ⟶ Hg_2Cl_2\)

Step-by-step solution

Write the formula for each ion

Silver ion: \(Ag^+\) Lead(II) ion: \(Pb^{2+}\) Mercury(I) ion: \(Hg_2^{2+}\) Chloride ion: \(Cl^-\)

Write the formulas for the insoluble chloride salts

Silver chloride: \(AgCl\) Lead(II) chloride: \(PbCl_2\) Mercury(I) chloride: \(Hg_2Cl_2\)

Write the skeletal net ionic equations for the precipitation reactions

Silver ion + Chloride ion ⟶ Silver chloride Lead(II) ion + Chloride ion ⟶ Lead(II) chloride Mercury(I) ion + Chloride ion ⟶ Mercury(I) chloride

Balance the net ionic equations

Silver ion + Chloride ion ⟶ Silver chloride \(Ag^+ + Cl^- ⟶ AgCl\) Lead(II) ion + 2 Chloride ions ⟶ Lead(II) chloride \(Pb^{2+} + 2Cl^- ⟶ PbCl_2\) Mercury(I) ion + 2 Chloride ions ⟶ Mercury(I) chloride \(Hg_2^{2+} + 2Cl^- ⟶ Hg_2Cl_2\) Now we have the balanced net ionic equations for the precipitation reactions of silver ion, lead(II) ion, and mercury(I) ion with chloride ion.