Happy National Mole Day!

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Ingenium - Canada's Museums of Science and Innovation

You might be thinking we’re honouring those funny-looking, burrowing creatures — but National Mole Day is actually in honour of a different kind of mole.

Celebrated annually on October 23 from 6:02 a.m. to 6:02 p.m., Mole Day commemorates Avogadro’s Number (6.02 x 1023), which is a basic measuring unit in chemistry. Chemists and chemistry students around the world celebrate Mole Day with various activities related to chemistry and moles.

For a given molecule, one mole is a mass (in grams) whose number is equal to the molar mass of the molecule. For example, the water molecule has a molar mass of 18, therefore one mole of water weighs 18 grams. Similarly, a mole of neon has a molar mass of 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.

Still scratching your head and trying to make sense of it all? Musician Michael Offutt explains it in a fun and understandable way in his song, The Mole is a Unit.

Are you a Canadian student who loves chemistry? Considering joining the Canadian Chemistry Olympiad!

A mole is an animal that burrows in the ground,

Or a spot on your chin that you gotta shave around.

But there’s another kind of mole of interest to me,

That’s the kind of mole they use in chemistry.

(Chorus) A mole is a unit, or have you heard,

Containing six times ten to the twenty-third,

That’s a six with twenty-three zeros at the end,

Much too big a number to comprehend.

Say you had a mole of pennies to distribute ‘round the world,

Give to each of the six billion grown-ups, boys and girls,

There wouldn’t be a single soul down and out of luck,

Cause everybody in the world would get a trillion bucks.

Or say you had a mole of paper and stacked it toward the sky,

Paper’s awful thin, but that pile would get so high,

It’d reach up into outer space, in fact I think you’d find,

It’d go up to the moon and back, eighty billion times.


Suppose a mole of marshmallows fell upon the planet,

Over each square inch of land and sea, think that you could stand it?

The layer would be twelve miles high and of course block out the sun,

We’re talking close to five million trillion tons.

Well, maybe we could save ourselves if we all started eatin’,

One marshmallow each second, not two cause that’d be cheatin’.

With six billion people munching, how long do you think it’d take?

Forty million years – and that’s without a bathroom break.


But say you had a mole of atoms, would the pile be immense,

Should I say the answer now, or leave you in suspense?

Well, atoms are so very, very small, you understand,

You could hold a mole of atoms in the palm of your hand.

So shake a little sugar in the middle of your palm,

Now you don’t want to spill it, so try and stay calm.

You hardly can imagine and barely realize,

There’re more atoms in that sugar than stars up in the sky.


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Sonia Mendes

Sonia Mendes is the English Writer/Editor for Ingenium. She loves digging behind the scenes to tell the quirky, colourful stories of museum life and all things related to science and innovation.