Question

On being heated at 120 degree Centigrade, gypsum (CaSO4.2H2O), gives plaster of paris. How much pure gypsum must be heated to obtain 14.5 kg of plaster of paris ? ( Relative Atomic masses : Ca=40, S=32, O=16, H = 1)

Answer 1

Ans 17.2 kg
Soln
1 mole or 172 gm CaSO4.2H2O gives 1mole or 145 gm CaSO4.(0.5)H2O. so 14.5 kg plaster of paris needs 17.2 kg gypsum
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