Stoichiometry Module: General Stoichiometry
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General Stoichiometry

S'Mores Example

A balanced chemical equation is very similar to a recipe. Clicking on the s'more on the left will show you more of the similarities between cooking and stoichiometry.

A balanced chemical equation gives you the ingredients (reactants) and the final food (products). The stoichiometric coefficients tell you how much reactants are needed to make a given amount of products.

For example methane (CH4) is the major component of natural gas. When burned in the presence of oxygen gas, carbon dioxide and water are produced. If you have used a Bunsen burner in the laboratory or used a natural gas stovetop, you have seen this reaction. The balanced chemical equation representing this process is:

Move mouse over equation to see names and molecules; click on mouse above to see all molecules at once.

This equation tells us that one molecule of methane will react with two molecules of oxygen to form one molecule of carbon dioxide and two molecules of water. When methane and oxygen undergo this reaction, they will always react in this proportion.

How many molecules of oxygen are needed to react with 20 molecules of methane?

10 20 40 60

Good! If one molecule of methane reacts with two molecules of oxygen and they always react in this ratio, then 20 molecules of methane would react with 40 molecules of oxygen.

Remember one molecule of methane always reacts with two molecules of oxygen. Try again