Question

On being heated 120°C, gypsum (CaSO4•2H2O), gives plaster of paris. How much pure gypsum must be heated to obtained 14.5 kg of plaster of paris?​

Answer 1

17.18 g of pure gypsum

Explanation:

molar mass of gypsum is 172 g/mol

When 172 g of gypsum is heated at 120°C it gives 145.14 g of plaster of paris  

172 g of gypsum → 145.14 g of POP

x g of gypsum → 14.5 g of POP

x = 14.5 × 172 / 145.14

  = 17.18 g of pure gypsum