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.
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.
Disposal.
Excess bromine
water can be ‘neutralized’ to harmless bromide by reacting it with a few
drops of 1 M sodium bisulfite solution or 1 M sodium thiosulfate solution.
Add either of these solutions with stirring until the red color of the
bromine water becomes colorless.