Question

When chlorine gas is passed in lime water, it forms chemical compound 'M' (main constituent of bleaching powder) and 'N' (used for bleaching in textile industry). Identify the correct option.

• A. 'X' = \(CO_2\); 'Y' = \(HCl\)
• B. 'X' = \(HCl\); 'Y' = \(Cl_2\)
• C. 'X' = \(Cl_2\); 'Y' = \(Ca(OH)_2\)
• D. 'X' = \(Cl_2\); 'Y' = \(CaCl_2\)

Hint:

Bleaching powder is produced by the action of chlorine gas on dry slaked lime [\(Ca(OH)_2\)].
Be careful not to use liquid lime water; the reaction requires dry slaked lime to yield stable solid bleaching powder.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question describes the industrial chemical preparation of bleaching powder. We need to identify the reactants 'X' (chlorine gas) and 'Y' (dry slaked lime) that react together to form bleaching powder.

Step 2: Key Formula or Approach:
The chemical equation for the manufacturing of bleaching powder is:
\[ Ca(OH)_2\text{(s)} + Cl_2\text{(g)} \to CaOCl_2\text{(s)} + H_2O\text{(l)} \]

Step 3: Detailed Explanation:

• Bleaching powder is chemically named calcium oxychloride, with the formula \(CaOCl_2\) (often represented more accurately as \(Ca(OCl)_2\)).

• It is prepared on an industrial scale using Hasenclever's or Bachmann's plant by passing chlorine gas over dry slaked lime.

• The reactants involved in this process are:
- Chlorine gas (\(Cl_2\)), represented as reactant 'X'.
- Dry slaked lime (\(Ca(OH)_2\)), represented as reactant 'Y'.

• When chlorine gas is passed through the slaked lime, they react to produce calcium oxychloride (\(CaOCl_2\), compound 'M') and water:
\[ Ca(OH)_2 + Cl_2 \to CaOCl_2 + H_2O \] - This compound \(CaOCl_2\) is the main constituent of commercial bleaching powder, which is widely used as a bleaching agent in textile and paper industries, and as a disinfectant in water treatment.

• Therefore, 'X' is \(Cl_2\) and 'Y' is \(Ca(OH)_2\), matching Option (C).


Step 4: Final Answer:
The correct reactants are 'X' = \(Cl_2\) and 'Y' = \(Ca(OH)_2\).