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You've Heard of Pi Day, Now Celebrate Mole Day

Tuesday, October 18, 2022

Mole Day is October 23rd  every year, and a great opportunity for educators to teach students (and refresh everyone else's memory) about this special number concept often used in Chemistry. If you need a refresher, never fear. Wikipedia is here!

Think of the Mole like the term "a dozen": Whether you have a dozen donuts or a dozen pickles, you can be sure that you have the same number of each for, uh, a donut and pickle party? Ok, the comparison may be culinarily off base, but if you have twelve hungry students, you can't go wrong with having a dozen of each item for choice as a snack.  In the case of the Mole, however, it's not donuts or pickles-- a Mole is used to count the number of things much smaller. A very large number of a very small things.

And now, for the small print. Wikipedia defines a Mole as, "The quantity amount of substance is a measure of how many elementary entities of a given substance are in an object or sample.... the mole is defined as containing exactly 6.02214076×10'23 elementary entities. Depending on what the substance is, an elementary entity may be an atom, a molecule, an ion, an ion pair, or a subatomic particle such as an electron. For example, 10 moles of water (a chemical compound) and 10 moles of mercury (a chemical element), contain equal amounts of substance and the mercury contains exactly one atom for each molecule of the water, despite the two having different volumes and different masses." That number, shortened, is 6.02 x 10'23, or what many folks will recognize as something called Avogadro's number.

A Few Fun Things About Moles

  • If we were to wrote out the word Mole a “mole” (or mol) of times, it would stretch to the next nearest galaxy to us (Canis Major), beyond the Milky Way. That is because there are 39,370 inches in a km, and the next nearest galaxy is 236,000,000,000,000,000 km away, which gives us about 23 digits.
  • Thinking of big numbers and moles, here’s an interesting article by Randall Munroe on what might happen if we had a mole (10^23) of moles (little furry rodents). Hint: it wouldn’t be pretty! That many moles would cover the entire surface of the earth to 80 km deep, which further suggests how tiny atoms really are.
  • Although Moles' namesake animals are often considered pests by gardeners because of their tendency to dig with abandon, they're actually very important housekeepers and gardeners themselves, eating subterranean pests and aerating soil. They're just a little misunderstood, just like the small but mighty Mole. 

This item was submitted by Kevin Anderson, DPI Science Consultant, in collaboration with DPI's Education Information Services.