Question

how is plaster of Paris prepared. why is temperature control necessary during its preparation. how does it react with water.​

Answer 1

Explanation:

a) It is prepared by heating gypsum to a temperature of 100° C in a kiln. It loses 3/4th of its water of crystallisation and forms plaster of Paris as seen in the Equation above.

b) The Temperature should be controlled carefully b/w 393 - 403K, otherwise above this temperature (say 473K), the whole of the water of Hydration is Lost and the Gypsum gets dead burnt.

c) When mixed with water, POP quickly solidifies into Gypsum by evolution of heat and also expands slightly.

equation: 2CaSO4•(1/2)H2O + 3H20 -> 2CaSO4•2H20

Hope it helped you out

Answer 2

Answer:

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Plaster of paris is prepared by heating calcium sulfate dihydrate, or gypsum, to 120–180 °C (248–356 °F). With an additive to rétard the set, it is called wall, or hard wall, plaster, which can provide passive fire protection for interior surfaces.