- By Muneeb Jamal
1. Bleaching Powder:
The chemical substance which used to remove color from a colored material by chemical materials into colorless substance is called bleaching powder. Its chemical name is calciumoxy chloride i-e ca(ocl)cl.
2. Laboratory Preparation Of Bleaching Powder:
In the laboratory bleaching powder can be prepared by shaking freshly prepared slaked lime Ca(oH)2. In a jar of chlorine.
Ca(oH)2 + Cl2---> Ca(ocl)Cl + H2o
3. Industrial Preparation Of Bleaching Powder:
Bleaching powder is prepared industrially by heating slaked lime with chlorine in hasenclever’s plant.
3.1. Construction Of Plant:
Plant consists of four cylindrical pipes which are 2-3 meter long, these pipes are arranged in horizontal position. Each cylindrical pipe has a rotating shaft which help the movement of slaked lime in these pipes.
Slaked lime is dipped from the top of the topmost cylinder through a hopper. Chlorine gas is introduced from the bottom i-e the lowest pipe, it moves in opposite direction of lime. The temperature is kept at 40C due to complete absorption of chlorine, a saturated solution of bleaching powder is formed. The unreached traces of chlorine is removed by passing hot air, the bleaching powder is collected in barrels and kept in wooden vats.
Ca(oH)2 + Cl2 ---> Ca(ocl) C + H2o.