Question
Thu March 27, 2014 By: Sanskrati Gawande

describe the preparation and use of 

quick lime

plaster of paris

Expert Reply
Thu March 27, 2014
Quick lime or Calcium oxide (CaO)
It is prepared on a commercial scale by heating limestone(CaCO3) in a rotary kiln at 1070-1270 K.
 
CaCO3     CaO  + CO2
The carbon dioxide is removed as soon as it is produced to enable the reaction to proceed to completion.
 
Uses:
It is an important primary material for manufacturing cement and is the cheapest form of alkali.
It is used in the manufacture of sodium carbonate  from caustic soda.
 
Plaster of Paris or Calcium Sulphate( CaSO4. 1/2H2O)
It is a hemihydrate of calcium sulphate and is obtained when gypsum is heated to 393K.
 
2(CaSO4.2H2O)  →   2(CaSO4).H2O + 2H2O
 
Uses:
•Used in  hospitals as  plaster for supporting fractured bones in the right position.
•Used for making decorative materials and for making surfaces smooth.
•Used as a fire-proofing material
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