How many grams are in 2.0 moles of iron(III) carbonate?

Explanation:

1 mole is equal to 1 moles Iron(III) or 832.29538 grams, so 2 moles Iron(III) = 1664.59076 grams

The chemist needs to react 40 g of sulfur with 60 g of oxygen to make 100 g of sulfur trioxide.

Explanation:

2S (s) + 3O₂ (g) → 2SO₃ (g)

64g    + 96g     →  160 g

32g    + 48g     →   80 g

   x     +     y      →  100 g

1 mol SO₃ ___ 80g

     n 100g

         n = 1.25 mol SO₃

1 mol S ___ 32 g

1,25 mol S __ 40 g

1 mol O₂ ___ 32 g

1,875 mol O₂ ___ 60 g