Explain why:

(a) It is necessary to find out the ratio of reactants required in the preparation of sodium sulphate.

(b) Fused calcium chloride is used in the preparation of FeCl3.

(c) Anhydrous FeCl3 cannot be prepared by heating hydrated iron (III) chloride.

(a) Since sodium hydroxide and sulfuric acid are both soluble, the excess of any of them cannot be removed by filtration. Therefore, it is important to determine the amount of reactants needed in the preparation of sodium sulfate.

(b) Combined calcium chloride is used to keep iron chloride dry as it is more deliquescent.

(c) In the case of hydrated ferric chloride, HCl acid is released, and the basic salt is ferric oxide (FeOCl). Therefore, anhydrous ferric chloride cannot be prepared by heating its hydrate.