write down the preparation of chlorinated lime along with chemical properties
Answers
Answer:
(a) Bleaching powder is Calcium oxychloride (CaOCl
2
). It is prepared by passing chlorine gas over dry slaked lime.
Reaction: Ca(OH)
2
+Cl
2
→CaOCl
2
+H
2
O
(b) When bleaching powder reacts with dilute sulphuric acid, it produces chlorine gas.
Reaction: CaOCl
2
+H
2
SO
4
→CaSO
4
+Cl
2
(g)+H
2
O(l)
(c) Two important uses of bleaching powder are-
(i) It is used for disinfecting the drinking water supply.
(ii) It is used in the manufacture of chloroform.
Answer:
Hint: Cl2 acts as a permanent bleaching agent because its bleaching action is due to oxidation.
Cl2+H2O→2HCl+ [ O ] organic colouring compound + [ O ] →colourless matter
While SO2 acts as a temporary bleaching agent because its bleaching action is due to reduction.
Complete Solution :
The chemical name of bleaching powder is calcium hypochlorite.it is manufactured by the action of chlorine on slaked lime (Ca(OH)2. The chemical formula of bleaching powder is CaOCl2.H2O.
2Ca(OH)2+ 2Cl2→CaOCl2+ 2H2O+CaCl2
The composition of bleaching powder is Ca(OCl)2.CaCl2.Ca(OH)2.2H2O . Industrially bleaching powder is manufactured in Bachmann’s plant or Hosenclever plant.
- Bleaching powder is a yellowish powder with a strong smell of chlorine. When it expose to air, it absorbs the moisture and reacts with carbon dioxide (CO2) and loses chlorine gas (Cl2). The obtained chlorine is known as ‘available chlorine’ which reacts with water and loses its yellow colour due to the formation of HCl and HOCl. HOCl on dissociation gives nascent oxygen (O) which is responsible for the oxidizing and bleaching property of bleaching powder.
CaoCl2+CO2→CaCO3+Cl2Cl2+H2O→HCl+HOClHOCl→HCl+ [ O ]
Uses of bleaching powder –
It is used as disinfectant and germicide, so it is used mainly for the sterilization of drinking water.
It is used in the manufacturing of chloroform.
It is used for making unshrinkable wool and bleaching cotton, wood pulp.
Note: In the presence of a slight amount of dilute acid the evolution of nascent oxygen