What Is a Good Analogy for the Mole Concept?

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The best analogy for a mole is a dozen eggs. Just as a dozen eggs is a convenient unit of measure for bakers and chefs, the concept of a mole provides chemists with a convenient unit of measure for dealing with atoms and molecules. Just as a dozen eggs is equal to 12 eggs, regardless of their size or color, one mole of eggs contains exactly 6.02 x 10^23 eggs.

Moles are used by chemists because they deal with such large numbers. Atoms and molecules are so incredibly small that scientists needed to invent a convenient unit of measure for counting atoms and molecules. The numerical value for a mole comes from the number of carbon atoms in a basic unit of mass. Twelve grams of carbon-12 contain exactly 6.02 x 10^23 carbon atoms. One mole of hydrogen or oxygen atoms contains a different amount, or mass, of material; but it contains the same number of molecules.

Where a baker may order three dozen eggs rather than 36 eggs, a chemist will write an equation that calls for several moles of an element, rather than asking for an extraordinarily high number of molecules. Moles make the jobs of chemists easier, just like the concept of a dozen eggs makes the job of a chef easier.