The correct answer is MgSOâ‚„.7Hâ‚‚O.
The hydrate of magnesium sulfate goes through dehydration due to action of heat. This procedure can be represented chemically as follows:
MgSOâ‚„.XHâ‚‚O (5.018 g) = MgSOâ‚„ (2.449 g) + XHâ‚‚O (2.569 g)
The number of moles of H2O evolved = 2.569 / molecular weight
= 2.569 / 18 = 0.1427
Number of moles of MgSOâ‚„ produced after decomposition,
= 2.449 / molecular weight
= 2.449 / 120.37
= 0.0203
Now dividing both these numbers to obtain the mole ratio, which prevails between MgSOâ‚„ and Hâ‚‚O
For H2O = 0.1427 / 0.0203 = 7.02 or 7
Therefore, the formula for the hydrate is MgSOâ‚„.7Hâ‚‚O.
