Iron oxide, known as hematite, is the main source of iron for the steel industry. It is created when iron and oxygen combine in a thermal decomposition reaction. It can be described using the equation 4Fe + 3O2 ➔ 2Fe2O3. If 19.2 grams of O2 reacts with iron to form iron oxide, how much iron, in grams, was used in the reaction? Use equations to help you solve for the answer.