NCERT Exemplar Solutions
Class 10 - Science - CHAPTER 2: Acids, Bases and Salts - Short Answer Questions
Question 39

Question. 39

39. In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.

Answer:

Main reaction (electrolysis of brine): \(\mathrm{2NaCl(aq) + 2H_2O(l) \to 2NaOH(aq) + Cl_2(g) + H_2(g)}\).
X = \(\mathrm{Cl_2}\) (chlorine gas).
Reaction with lime water: \(\mathrm{Ca(OH)_2 (s) + Cl_2 (g) \to CaOCl_2 (s) + H_2O}\).
Y = calcium oxychloride (bleaching powder, \(\mathrm{CaOCl_2}\)).

Detailed Answer with Explanation:

Steps: Electrolysis of NaCl gives NaOH, Cl₂ and H₂. Chlorine reacts with slaked lime to form bleaching powder (calcium oxychloride).

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NCERT Exemplar Solutions Class 10 – Science – CHAPTER 2: Acids, Bases and Salts – Short Answer Questions | Detailed Answers