CBSC Science

Acid-bases and salts * Preparation and uses of important compounds. I) Caustic Soda (Sodium Hydroxide, NaOH) Preparation of Sodium hydroxide Preparation: In the process of electrolytic decomposition of brine (aqueous solution of sodium chloride), brine decomposes to form sodium hydroxide. 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g) In this process, chlorine is moved towards anode and hydrogen gas is moved towards cathode as by products. This whole process is known as Chlor – Alkali process. Uses: Sodium hydroxide is used for degreasing of metals, manufacturing of paper, soap, detergents, artificial fibres, etc. II) Bleaching Powder (Calcium Oxychloride, CaOCl2) Preparation of Bleaching powder Preparation: Bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH)2]. Ca(OH)2 + Cl2→ CaOCl2 + H2O Uses: (i) It is use for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry; (i...