Stoichiometry: Understanding the Mole

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The "Why?" and "How?" of the Mole

The Mole is everywhere in chemistry but it's an abstract concept and tough to understand. Part of the problem is that we use the mole in different ways to discuss the very small (e.g. molecules) and the large (mass and volume). To be successful you must understand how the mole is being used in a given context.

Key Mole Ideas:

  • We use Avogadro's Number (6.02 x 1023) with the very small (e.g. atoms and molecules). This is the only place we use Avogadro's Number!

  • We use mass (grams) for the quanties large enough to measure in the lab.

  • We use Molar Mass to convert between the small (micro) and large (macro) world.
Balanced chemical equations provide ratios of moles that can be used to calculate amounts of reactants and products in a chemical reaction. We can think of the coefficients as moles!

More Help and Practice:

The Mole Map

Mole Map

Printable Mole Map