2.4.3 Chemicals from Common Salt · Part 2

the actual composition is quite complex. Ca(OH) + Cl → CaOCl + H O Figure . Figure . Figure . Figure . Figure . Important products from the chlor-alkali process Bleaching powder is used – (i) for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry; (ii) as an oxidising agent in many chemical industries; and (iii) to make drinking water free from germs. Baking soda The baking soda is commonly used in the kitchen for making tasty crispy pakoras, etc. Sometimes it is added for faster cooking. The chemical name of the compound is sodium hydrogencarbonate (NaHCO ). It is produced using sodium chloride as one of the raw materials. NaCl + H O + CO + NH NH Cl + NaHCO (Ammonium (Sodium chloride) hydrogencarbonate) Did you check the pH of sodium hydrogencarbonate in Activity . ? Can you correlate why it can be used to neutralise an acid? It is a mild non-corrosive basic salt. The following reaction takes place when it is heated during cooking – 2NaHCO Na CO + H O+CO Heat   (Sodium (Sodium hydrogencarbonate) carbonate) Sodium hydrogencarbonate has got various uses in the household. Uses of Baking soda (i) For making baking powder, which is a mixture of baking soda (sodium hydrogencarbonate) and a mild edible acid such as tartaric acid. When baking powder is heated or mixed in water, the following reaction takes place – NaHCO + H + → CO + H O + Sodium salt of acid (From any acid) Carbon dioxide produced during the reaction can cause bread or cake to rise making them soft and spongy. (ii) Sodium hydrogencarbonate is also an ingredient in antacids. Being alkaline, it neutralises excess acid in the stomach and provides relief. (iii) It is also used in soda-acid fire extinguishers. Washing soda Another chemical that can be obtained from sodium chloride is Na CO .10H O (washing soda). You have seen above that sodium carbonate can