Stoichiometry Module: General Stoichiometry
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General Stoichiometry

Since the number of molecules (such as 20 molecules of methane) would be impossible to measure in a common laboratory experiment, chemists typically deal in units of moles.


What is a mole?

How many moles of water can be produced when seven moles of methane are burned?

7 14 28

Remember that when one molecule of methane is burned, two molecules of water are produced (from the stoichiometric coefficients in the balanced chemical equation). These numbers can be increased by any factor and the proportion will remain the same (24 molecules (or two dozen) molecules of methane will produce 48 molecules (or four dozen) of water when burned). If you are having difficulty with the concept of a mole, click the help above.

Good! The stoichiometric coefficients in the balanced chemical equation tell you that for every one mole of methane that is burned, two moles of water are produced. Therefore, when seven moles of methane are burned, 14 moles of water must be produced.