Experiment 41

Objective

To identify the presence of chloride ions in a supplied sample using silver nitrate and ammonium hydroxide.

Introduction

When chloride ions are present in a solution, the addition of silver nitrate produces a white precipitate of silver chloride (AgCl), which is insoluble in nitric acid but dissolves in ammonium hydroxide. In ammonium hydroxide, silver chloride forms a soluble complex, diammine silver chloride.

Reaction Equations:

1.    Formation of silver chloride precipitate:

NaCl (aq)+AgNO3​ (aq)→AgCl↓+NaNO3​ (aq)

2.    Dissolution of AgCl in ammonium hydroxide:

AgCl+2NH4​OH→[Ag(NH3​)2​]Cl+H2​O

Materials

Chemicals

●      Supplied sample containing chloride ions

●      Silver nitrate (AgNO₃)

●      Ammonium hydroxide (NH₄OH)

Apparatus

●      Test tube

●      Test tube holder

●      Bunsen burner

Preparation of Reagents

●       Dissolve 3.657 g of the supplied sample in 250 mL of distilled water.

Procedure

1.    Testing for Chloride Ions:

●      Take 5-6 mL of the prepared sample solution in a test tube.

●      Add 2-3 mL of silver nitrate (AgNO₃) solution to the test tube.

●      Observe the formation of a white precipitate.

2.    Confirmation with Ammonium Hydroxide:

●      Add a few drops of ammonium hydroxide (NH₄OH) to the test tube containing the white precipitate.

●      Observe whether the precipitate dissolves, indicating the presence of chloride ions

Observation

A white precipitate forms upon adding silver nitrate, indicating the presence of chloride ions. The precipitate dissolves completely upon adding ammonium hydroxide, confirming the presence of chloride ions.

Questions

1.    What color forms during the chloride test?

2.    Which reagent is used in the chloride test?

3.    What happens when ammonium hydroxide is added to the precipitate?