5.45 grams of magnesium sulfate heptahydrate is how many moles?

5.45 g is 0.0221 moles of magnesium sulfate heptahydrate.

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.