water of crystallisation

Question 1

method of heating in a crucible

Answer 1

1. weigh an empty clean dry crucible and lid
2. add 2g of hydrated calcium sulphate to the crucible and weigh again
3. heat with bunsen burner
4. weigh the crucible and contents again
5. heat again and reweigh until u get a constant mass

Question 2

why should a lid be used?

Answer 2

improves accuracy - prevents loss of solid from the crucible

Question 3

why use small amounts of CaSO4

Answer 3

to be make sure decomposition is complete