Today, October 23 (or 10/23, as it’s written the American way), from 6:02 am to 6:02 pm, is Mole Day. No, it’s not a day for freckles, spies, Mexican sauce, or cute little burrowing mammals. Rather it’s the day to celebrate the chemical unit the “mole.”
What is a mole, you ask, having forgotten high school chemistry. A mole of something is 6.02 x 10^23 of it (kind of like a dozen of eggs is 12 eggs, a mole of eggs is 602,000,000,000,000,000,000,000 eggs*.)
*okay, technically, it’s 602,214,129,270,000,000,000,000 eggs (give or take a few quintillion – scientists can’t agree on the exact number).
So, with that out of the way, here are 5 fun facts about the mole and Mole Day:
1. The mole is attributed to 18th century Italian scientist Amedeo Avogadro, whose full name is Lorenzo Romano Amedeo Carlo Avogadro di Queregna e di Cerreto. Man, that’s a long name, but it somehow fits the long number that now bears his name (6.02 x 10^23 is called Avogadro’s Constant). His parents called him Amedeo Carlo Avogadro.
We won’t get into the technical aspects, but in 1811 Avogadro proposed a law (now known as Avogadro’s Law) stating that equal volume of all gasses, at the same temperature and pressure, have the same number of molecules.
As with many scientific accomplishments of that age, Avogadro’s findings were promptly ignored. It took about a hundred years for the scientific community to get around to appreciating what he’s done. In 1909, French chemist and Nobel laureate Jean Baptiste Perrin proposed that quantity of molecules be called “Avogadro’s Constant.”
2. Mole Day was proposed in an article in The Science Teacher in early 1980s. Inspired by the article, Maurice Oehler, a chemistry teacher (now retired) in Prairie du Chien, Wisconsin, created the National Mole Day Foundation in 1991.
3. Did you know that the Mole Day has annual themes? Here they are:
| 1991 | The Mole The Merrier |
| 1992 | Go For The Mole |
| 1993 | Mole Out The Barrel |
| 1994 | An Ace in The Mole |
| 1995 | Moledi Gras |
| 1996 | Molemorial Day |
| 1997 | We Dig Chemistry |
| 1998 | Ride the Molercoaster |
| 1999 | It’s A MOLE World |
| 2000 | Celebrate the Molennium |
| 2001 | Molar Odyssey |
| 2002 | Molar Reflections |
| 2003 | Rock ‘n Mole |
| 2004 | Pi a la MOLE |
| 2005 | Moles-Go-Round |
| 2006 | Mole Madness |
| 2007 | Secret Agent Double Mole Seven in Moles are Forever |
| 2008 | Remember the Alamole |
| 2009 | Molar Express |
| 2010 | Moles of the Round Table |
| 2011 | Molar Eclipse |
| 2012 | Animole Kingdom |
4. To help you celebrate, here’s the Molemorial Day song by Michael Offutt (that’s the theme of the Mole Day in 1996, when Offutt recorded the song). Actually Offutt created a whole album, titled “Molennium,” filled with songs about the mole.
5. As you can probably guess, a mole (6.02 x 10^23) is a VERY large number. But, what does a mole of moles look like? What if we release a mole of moles onto our planet? xkcd explains:
An eastern mole (Scalopus aquaticus) weighs about 75 grams, which means a mole of moles weighs (6.022×10^23)×75g≈4.52×10^22kg.
That’s a little over half the mass of our moon.
Mammals are largely water. A kilogram of water takes up a liter of volume, so if the moles weigh 4.52×10^22 kilograms, they take up about 4.52×10^22 liters of volume. You might notice that we’re ignoring the pockets of space between the moles. In a moment, you’ll see why.
The cube root of 4.52×10^22 liters is 3,562 kilometers, which means we’re talking about a sphere with a radius of 2,210 kilometers, or a cube 2,213 miles on each edge. (That’s a neat coincidence I’ve never noticed before—a cubic mile happens to be almost exactly 4/3pi cubic kilometers, so a sphere with a radius of X kilometers has the same volume as a cube that’s X miles on each side.)
If these moles were released onto the Earth’s surface, they’d fill it up to 80 kilometers deep—just about to the (former) edge of space:
