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Question
Calculate the percentage of water in ferrous sulphate crystals.
[Fe = 56, S = 32, O =16, H = 1].
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Solution
Ferrous sulphate is FeSO4.7H2O
Molecular mass of Ferrous sulphate is FeSO4.7H2O is:
Atomic mass of Fe + Atomic mass of S + Atomic mass of H + Atomic mass of O
= 56 + 32 + 1 x 14 + 16 x 11 = 278
278 parts by weight of crysta ls contain 126 parts of water
100 parts will contain = 126 x 100 / 278 = 45.32‰
So, the percentage of water in ferrous sulphate crystals is 45.32‰
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