Chemistry · May / June 2023 · Paper 11 · Question 9

Samples of two hydrated compounds are weighed and then dehydrated by heating. The anhydrous compounds are weighed and the results are shown. 3.97 g FeSO4•xH2O gives 2.17 g anhydrous FeSO4. 2.88 g CaSO4•yH2O gives 2.27 g anhydrous CaSO4. What are the values of x and y? [Mr: FeSO4, 152; CaSO4, 136; H2O, 18]

1. Ax = 5, y = 2
2. Bx = 5, y = 5
3. Cx = 7, y = 5
4. Dx = 7, y = 2

As printed in the paper