Give at least one method used to obtai the following chemical compound a- bleaching powder b- baking soda c- washing soda
Answers
Bleaching Powder:
Bleaching powder is also known as chloride of lime. It is a solid and yellowish white in colour. Bleaching powder can be easily identified by the strong smell of chlorine.
When calcium hydroxide (slaked lime) reacts with chlorine, it gives calcium oxychloride (bleaching powder) and water is formed.
Ca(OH)2 + Cl2 ⇨ CaOCl2 + H2O
Aqueous solution of bleaching powder is basic in nature. The term bleach means removal of colour. Bleaching powder is often used as bleaching agent. It works because of oxidation. Chlorine in the bleaching powder is responsible for bleaching effect.
Baking Soda:
Baking soda is another important product which can be obtained using byproducts of chlor-alkali process. The chemical name of baking soda is sodium hydrogen carbonate (NaHCO3 ) or sodium bicarbonate. Bread soda, cooking soda, bicarbonate of soda, sodium bicarb, bicarb of soda or simply bicarb, etc. are some other names of baking soda.
Baking soda is obtained by the reaction of brine with carbon dioxide and ammonia. This is known as Solvay process.
NaCl + CO2 + NH3 + H2O ⇨ NH4Cl + NaHCO3
In this process, calcium carbonate is used as the source of CO2 and the resultant calcium oxide is used to recover ammonia from ammonium chloride.
Properties of sodium bicarbonate:
Sodium bicarbonate is white crystalline solid, but it appears as fine powder.
Sodium hydrogen carbonate is amphoteric in nature.
Sodium hydrogen carbonate is sparingly soluble in water.
Thermal decomposition of sodium hydrogen carbonate (baking soda).
When baking soda is heated, it decomposes into sodium carbonate, carbon dioxide and water.
2NaHCO3 + heat ⇨ Na2CO3 + CO2 + H2O
Sodium carbonate formed after thermal decomposition of sodium hydrogen carbonate; decomposes into sodium oxide and carbon dioxide on further heating.
Na2CO3 ⇨ Na2O + CO2