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It’s Mole Day. What’s that?

( Mole Day Cake (

It’s Mole Day.

What’s that? Mole Dole is celebrated every Oct. 23 from 6:02 a.m. to 6:02 p.m. in commemoration of  Avogadro’s Number, according to the National Mole Day Foundation Inc. Web site (yes there is one).

What’s Avogadro’s Number? It is 6.02 x 1023 , a basic measuring unit in chemistry discovered by the 18th century chemist Amadeo Avogadro. This explains the time and day it is celebrated: 6:02 10/23.

Why is called Mole Day? Again from the Web site:

For a given molecule, one mole is a mass (in grams) whose number is equal to the atomic mass of the molecule. For example, the water molecule has an atomic mass of 18, therefore one mole of water weighs 18 grams. An atom of neon has an atomic mass of 20, therefore one mole of neon weighs 20 grams. In general, one mole of any substance contains Avogadro’s Number of molecules or atoms of that substance. This relationship was first discovered by Amadeo Avogadro (1776-1858) and he received credit for this after his death.

Mole Day, which appears to have started in 1991, was conceived to try to get children interested in chemistry, and on this day every year, schools around the world introduce activities involving chemistry, and, of course moles. Each year has its own theme; you can see past themes here. (Last year was Molar Eclipse. Enough said.)

Mole jokes are a big part of Mole Day. For example:

Q: Why was there only one Avogadro?

A: When they made him, they broke the Moled

The Fayetteville Christian School’s science page has some suggestions for celebrating Mole Day, including “Drink a glass of molasses milk (201g [ 7.1 oz ] of C6H12NNaO3S = 1 mole) at 6:02am & pm.”

And some chemistry websites:

Crash Course  –  Hank Green teaches chemistry in 30 lessons.

Periodic Table of Videos – Element by element, this looks at different chemical reactions like the barking dog and the cheeseburger in hydrochloric acid.

Royal Institution – Explores chemical curiosities.





Valerie Strauss covers education and runs The Answer Sheet blog.



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Valerie Strauss · October 23, 2013

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