How do i find the excess reactant of 2 Fe(OH)3 + 3 H2SO4 = Fe2(SO4)3 + 6 H2O? Given: 3.0 mol Fe(OH)3 and 5.7 mol H2SO4

Answer 1

So the equation is balanced for us, which is nice. That makes answering the question much easier.

The easiest way to do these problems is always just to figure out how many moles of product you can make based on how many moles of each starting material you have. Whichever starting material makes the least amount of product is your limiting reagent (so all other reagents would be in excess).

In this case 2 moles of Fe(OH)₃ are required to make 1 mole of Fe₂(SO₄)₃. We have 3 moles of Fe(OH)₃ so we can make 1.5 moles of Fe₂(SO₄)₃. We need 3 moles of H₂SO₄ to make 1 mole of Fe₂(SO₄)₃. We have 5.7 moles of H₂SO₄ so we can make 1.9 moles of Fe₂(SO₄)₃. H₂SO₄ allows us to make more moles of product, so it must be in excess.

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