Question

What is Bromine water? Its preparation, properties and uses?

Answer 1

Two methods are described here. The first one requires the use of liquid bromine and a working fume hood. Method I. Bromine water from Liquid Bromine In order to make 50-mL bromine water, you will need: Glass bottle with screw cap, label the bottle “Br2(aq)” This bottle must have a capacity of about 100-mL 50-mL water (preferably distilled water) a bottle of liquid bromine Transfer the water to the bottle. Working in a fume hood, decant the vapors only from a bottle of liquid bromine to the bottle with the water. The vapors are red in color and heavier than air. After the airspace above the water in the bottle is filled with red bromine vapors, cap both bottles. Swirl or gently shake the bottle containing the water in order to mix the contents. The bromine will readily dissolve and the solution will become yellow in color. The process should be repeated at least once more. Typically bromine water should be orange in color so that it can be seen when diluted. Method II. Bromine water from Chlorine-based household bleach and Sodium Bromide. Flinn Scientific has developed a convenient method for the preparation of bromine water from sodium bromide, household bleach and 1 M hydrochloric acid. Their method does not require the use of liquid bromine. In order to make 50-mL bromine water, you will need: Glass bottle with screw cap, label the bottle “Br2(aq)” 1.1 g sodium bromide, NaBr 10.7 mL 1 M HCl 7.6 mL sodium hypochlorite (household laundry bleach) 32 mL water (preferably distilled water) Dissolve the NaBr in the HCl and transfer to the labeled bottle. Add the sodium hypochlorite to the bottle and swirl to mix the reagents. Keep the bottle capped when not in use Bromine water is a highly oxidizing intense yellow to red mixture containing diatomic bromine (Br2) dissolved in water (H2O).[1] It is often used as a reactive in chemical assays of recognition for substances which react with bromine in an aqueous environment with the halogenation mechanism. The most common compounds that react well with bromine water are phenols, alkenes, enols, the acetyl group, aniline, and glucose. In addition, bromine water is commonly used to test for the presence of an alkene which contains a double covalent bond which reacts with the bromine water which changes its color from an intense yellow to a colorless solution. Bromine water is also commonly used to check for the presence of an aldehyde group in compounds. In this reaction as well the color of bromine water is changed to colorless from yellow (oxidation process).