Chemistry – The Periodic Table - Group VII properties | e-Consult

Experimental Procedure:

1. Setup: Place a small amount of bromine water in a conical flask. Add a few drops of sodium thiosulfate solution.
2. Observation: Observe the reaction carefully. A cloudy solution will form initially.
3. Heat: Gently warm the flask using a hot plate or by holding it in warm water.
4. Reaction: As the solution warms, the cloudiness will gradually disappear.

Safety Precautions:

• Bromine Water: Bromine water is corrosive and can cause burns. Wear safety goggles and gloves when handling it. Avoid contact with skin and clothing.
• Sodium Thiosulfate: Although relatively safe, avoid inhaling the powder.
• Heating: Use caution when using a hot plate or hot water to avoid burns.

Identifying the Product:

The product formed is bromine gas (Br₂). The disappearance of the cloudiness is due to the reaction of the bromine gas with the sodium thiosulfate (Na₂S₂O₃) in the solution. The balanced equation for this reaction is:

The disappearance of the cloudiness indicates that the bromine gas has reacted with the thiosulfate ions to form sodium bromide (NaBr) and sodium thiosulfate (Na₂S₄O₆). The reaction is a chemical test for the presence of bromine.