Our Objective

Identify the bleaching powder from the given set of samples and understand the chemistry behind the bleaching action.

The Theory

Bleaching powder is a light yellowish powder with a strong chlorine odour. Although it is soluble in water, the presence of contaminants prevents us from seeing a clean solution. The chemical formula of bleaching powder is Ca(OCl)2 and the chemical name is Calcium hypochlorite or Calcium oxychloride.

Bleaching powder is a water-soluble bleaching agent used in the textile industry. In several sectors, it's also utilised as an oxidizer and disinfectant. It's also worth noting that bleaching powder is made by reacting chlorine gas with dry slaked lime (Ca(OH)2). 

Bleaching powder is calcium oxochloride (CaOCl₂). On treatment with small quantity of dilute acid, it liberates hypochlorous acid which can easily furnish oxygen called nascent oxygen and thus acts as an oxidising and bleaching agent.

2CaOCl₂ (s) + H₂SO₄ (aq) →CaSO₄ (aq) + CaCl₂ (aq) + 2HClO (aq)

HClO → HCl + [O] (Nasent oxygen)

In this experiment, we shall make use of this bleaching reaction to identify the bleaching powder from the given samples of chemicals.

Uses of Bleaching Powder

• It is used for bleaching dirty clothes in the laundry, as a bleaching agent for cotton and linen in the textile industry.
• It is a strong oxidizing agent, hence used as an oxidizer in many industries
• It is used as a disinfectant which is used for disinfecting water to make potable water.

Learning Outcomes

• Students will be able to understand the chemistry behind the bleaching powder and will learn more about how it acts. 
• The experiment will help students to have better laboratory skills. 
• They will be able to understand the chemical aspects like the action of Nascent Oxygen that is playing the important role as well as the calcium hypochlorite. 
• This would help the students to know the practical uses of bleaching powder.