Editing Stoichiometry (section)

== Stoichiometric ratio ==
Stoichiometry is also used to find the right amount of one [[reactant]] to "completely" react with the other reactant in a [[chemical reaction]] – that is, the stoichiometric amounts that would result in no leftover reactants when the reaction takes place. An example is shown below using the [[thermite reaction]],{{citation needed|date=February 2024}}
: {{chem2|Fe2O3 + 2 Al -> Al2O3 + 2 Fe}}

This equation shows that 1&nbsp;mole of {{nowrap|[[iron(III) oxide]]}} and 2&nbsp;moles of [[aluminium]] will produce 1&nbsp;mole of [[aluminium oxide]] and 2&nbsp;moles of [[iron]].  So, to completely react with 85.0&nbsp;g of {{nowrap|iron(III) oxide}} (0.532&nbsp;mol), 28.7&nbsp;g (1.06&nbsp;mol) of aluminium are needed.
: <math>m_\mathrm{Al} = \left(\frac{85.0 \mbox{ g }\mathrm{Fe_2O_3}}{1}\right)\left(\frac{1 \mbox{ mol }\mathrm{Fe_2 O_3}}{159.7 \mbox{ g }\mathrm{Fe_2 O_3}}\right)\left(\frac{2 \mbox{ mol Al}}{1 \mbox{ mol }\mathrm{Fe_2 O_3}}\right)\left(\frac{26.98 \mbox{ g Al}}{1 \mbox{ mol Al}}\right) = 28.7 \mbox{ g}</math>