Answer:
1.381 moles Fe
Step-by-step explanation:
To find moles of Fe, you need to (1) convert grams Fe(NH₄)₂(SO₄)₂ to moles (using the molar mass) and then (2) convert moles Fe(NH₄)₂(SO₄)₂ to moles Fe (using the mole-to-mole ratio within the molecule). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 4 sig figs like the given value (392.2 = 4 sig figs).
Atomic Mass (Fe): 55.845 g/mol
Atomic Mass (N): 14.007 g/mol
Atomic Mass (H): 1.008 g/mol
Atomic Mass (S): 32.065 g/mol
Atomic Mass (O): 15.999 g/mol
Molar Mass (Fe(NH₄)₂(SO₄)₂):
55.845 g/mol + 2(14.007 g/mol) + 8(1.008 g/mol) + 2(32.065 g/mol) + 8(15.999 g/mol) = 284.045 g/mol
1 mole Fe(NH₄)₂(SO₄)₂ = 1 mole Fe, 2 moles N, 8 moles H, 2 moles S, 8 moles O
392.2 g Fe(NH₄)₂(SO₄)₂ 1 mole 1 mole Fe
----------------------------------- x ------------------- x ---------------------------------- =
284.045 g 1 mole Fe(NH₄)₂(SO₄)₂
= 1.381 moles Fe