Question

How will you prepare the following ? Give chemical reactions

(i) Plaster of Paris from Gypsum

also

(ii) Bleaching powder from slaked lime​

Answer 1

Answer:

i ) Gypsum rock is converted into gypsum plaster by driving off some of the chemically combined water. Heating gypsum at 120°C for one hour results in a hemi-hydrate (CaSO4. 1⁄2H2O) – with three quarters of the water removed. Gypsum hemi-hydrate is also known as Plaster of Paris.

ii) First dry the slaked lime is fed in to the hasenclever plant through the hopper present in the uppermost cylinder . After that the dry slaked lime is moved forward by the revolving blades of the rotating shaft . Meanwhile chorine gas is passed through the inlet of the lowermost cylinder which rises up to the uper cylinders and reacts with the dry slaked lime coming downward to form bleaching powder . This bleaching powder comes out through the outlet at the bottom of the innermost cylinder and collected in a vessel .