Question

Find the percentage of water of crystallisation in CuSO₄.5H₂O. (At. Mass Cu = 64, H = 1, O = 16, S = 32)

Answer 1

The relative molecular mass of CuSO₄.5H₂O

= 64 + 32 + (4 × 16) + 5 [(2 × 1) + 16]

= 160 + 90

= 250

250g of CuSO₄.5H₂O contains 90g of water of crystallization.

= `90/250 xx 100`

= 36 g

∴ Percentage of water of crystallisation in CuSO₄.5H₂O = 36%