Question

Explain Plaster of Paris.

Answer 1

Plaster of Paris is formed when gypsum is heated at a vry high temperature it's reaction is

Cuso4. 10h2o give rise cuso4.1/2h2o

Answer 2

Hey !!

Plaster of paris is calcium sulphate half hydrate and is called calcium sulphate hemi-hydrate. It is denoted as CaSO₄.1/2 H₂O or 2CaSO₄.H₂O or (CaSO₄)₂.H₂O. It is obtained by heating gypsum at 120°C

           CaSO₄.2H₂O --(120°C)--> CaSO₄.1/2H₂o + 3/2H₂O

On heating plaster of paris or gypsum over 170°C, it looses water of hydration and is converted into anhydrous calcium sulphate, known as dead burnt. Dead burnt has no ability of hydration and it does not set with water.

       Plaster of paris, when mixed with half of its amount of water by weight, becomes a paste which sets to a hard mass. This process is known as setting. Setting involved hydration leading to the formation of dihydrate. During setting, the volume increases.

NOTE :- This much information is enough for BOARD EXAMS AND FOR ANY OTHER COMPETITIVE EXAM !!

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