The formula of Iron(III) oxide is Fe2O3
In order to calculate the mass of iron in a given sample of iron(III) oxide, we must first know the mass percentage of iron in iron(III) oxide. This is calculated by:
[mass of iron in one mole of iron(III) oxide/ mass of one mole of iron(III) oxide] 100
= [(moles of iron Mr of iron) / (moles of Iron Mr of Iron + moles of Oxygen Mr of Oxygen)] 100
= [(2 56) / (2 56 + 3 16)] 100
= (112 / 160) 100
= 70%
Thus, in a 100g sample, the weight of iron will be:
100 * 70%
= 70 grams
