How much iron do you need to take to get 116g of iron scale Fe3O4? How much oxygen will be consumed in this reaction?
Let’s find the amount of the substance of the iron scale Fe3O4.
n = m: M.
M (Fe3O4) = 56 × 3 + 16 × 4 = 232 g / mol.
n = 116 g: 232 g / mol = 0.5 mol.
Let’s compose the reaction equation, find the quantitative ratios of substances.
3Fe + 2O2 = Fe3O4
For 1 mole of iron scale, there are 3 moles of iron. The substances are in quantitative ratios of 1: 3. The amount of the iron substance will be 3 times more than the amount of the iron scale substance.
n (Fe) = 3n (Fe3O4) = 0.5 mol × 3 = 1.5 mol.
Let’s find the mass of iron.
m = n M.
M (Fe) = 56 g / mol.
m = 1.5 mol × 56 g / mol = 84 g.
Let’s find the mass of oxygen.
For 1 mole of iron scale, there are 2 moles of oxygen. Substances are in quantitative ratios 1: 2. The amount of oxygen substance will be 2 times more than the amount of iron scale substance.
n (Fe) = 3n (Fe3O4) = 0.5 mol × 2 = 1 mol.
M (O2) = 32 g / mol.
m = 1 mol × 32 g / mol = 32 g.
Answer:; m (O2) = 32 g; m (Fe) = 84 g.