Question

An iron nail rusts when exposed to oxygen. According to the following reaction, how many grams of iron(III) oxide will be formed upon the complete reaction of 21.1 grams of oxygen gas with excess iron? 4Fe (s) + 3O2 (g) 2Fe2O3 (s)

Answer 1

number of moles of oxygen = (21.1 g / 32 g/mol) = 0.659 mol

number of moles of iron(III) oxide formed = (2 mole Fe2O3 / 3 mole O2) * 0.659 mol O2 = 0.439 mol

mass of Iron(III) oxide formed = 0.439 mol * 159.69 g/mol = 70.2 g