Stoichiometry, Moles, and Molecular Weight

A mole is the quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12 grams of carbon-12.  The number of atoms in twelve grams of carbon-12 is Avogadro's number, symbolized NA.  Avogadro's number is equal to 6.02 x 10²³ to three significant figures.  So, a mole of something, not unlike a dozen, baker's dozen, or gross, refers to a certain number of things.  A dozen eggs is twelve eggs.  A baker's dozen of muffins is thirteen muffins.  A gross of bottle-rockets is 144 bottle rockets.  Likewise, a mole of oranges is 6.02 x 10²³ oranges (so many oranges that it would take ~19 million years to count this number of oranges if counting a billion oranges per second!)