Experiment 35

Objective

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

Introduction

Bromide ions in a solution react with silver nitrate to produce a slightly yellow precipitate of silver bromide (AgBr). This precipitate is insoluble in nitric acid and only slightly soluble in ammonium hydroxide.

Reaction Equation:

NaBr (aq)+AgNO3​ (aq)→AgBr↓+NaNO3​ (aq)

Materials

Chemicals

●       Supplied sample containing bromide 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 Bromide 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 slightly yellow precipitate.

2.    Confirmation with Ammonium Hydroxide:

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

●      Note any changes in the precipitate’s appearance; slight solubility of the yellow precipitate in ammonium hydroxide indicates the presence of bromide ions.

Observation

The addition of silver nitrate produces a slightly yellow precipitate, indicating the presence of bromide ions. Upon adding ammonium hydroxide, the precipitate slightly dissolves, confirming the presence of bromide ions.

Questions

1.    What color forms during the bromide test?

2.    Which reagent is used in the bromide test?

3.    What happens when ammonium hydroxide is added?

4.    What is a bromide salt?