Experiment 19: Identify bleaching powder

Objective

To identify bleaching powder among given samples of chemicals

Materials required:

• Given four samples: bleaching powder; sodium chloride; calcium carbonate; and ammonium chloride
• dil. sulphuric acid
• flowers petals
• test tubes

Procedure:

• Put the arnd 1g of salts in different test tubes (marked A, B, C & D) and add 10mL water
• Take about 10 mL of dilute sulphuric acid in each of remaining four test tubes. Label them as E, F, G, and H
• Dip a small piece of coloured cloth or flower petal in test tube A
• Take out the cloth or flower petal from the test tube A and dip it in dil. sulphuric acid in test tube E and stir it gently with the help of a glass rod.
• Repeat the process for Test Tube B, C and D

Findings:

• No change in color observed in 3 petal when inserted in test tubes. However, for one of the test tubes, petal is decolorized

Conclusions:

• Sample which decolorizes the flower petal contains bleaching powder

Theory:

• Bleaching powder is a pale yellowish powder existing with a strong smell of chlorine. It is soluble in water but due to the presence of impurities, we never observe a clear solution. Its chemical formula is CaOCl2 with its chemical name as Calcium hypochlorite.