Answer:
5.45 g is 0.0221 moles of magnesium sulfate heptahydrate.
Step-by-step explanation:
The molecular formula of magnesium sulfate heptahydrate is Mg SO₄·7H₂O.
The molar mass of this compound is calculated adding the molar mass of each element:
Mg: 24. 3 g
S: 32. 1 g
O: 16 g
H: 1 g
Then the mass of a mole of Mg SO₄·7H₂O is:
24.3 g + 32.1 g +4(16 g) + 7(2(1) + 16) = 246.4 g.
if 246.4 g is 1 mole of Mg SO₄·7H₂O, then 5.45 g will be:
5.45 g *(1 mol / 246.4 g) = 0.0221 mol.