Moles are coming!

Moles are cute, at least this kind is! 

image taken from http://en.wikipedia.org/wiki/Mole_(animal)

You might not find the kind of mole you find in the lab quite so endearing at first, but you will soon come to realise that in science, you can't do without it...

So what is a mole?

1 mole is quite simply a number, 6.02 x 10²³ in fact! (This is known as Avogadro's number.)

You could have 1 mole of absolutely anything, it would just mean that you have 6.02 x 10²³ of whatever that might be. For example, you might have 1 mole of pennies - so that would be 6.02 x 10²³ pennies in total .... so how rich would you be if you had this many pennies I wonder ...

We use moles when we talk about chemicals and chemical reactions - at levels where using grams or absolute numbers of atoms wouldn't make sense. It is much easier to write 'mole' rather than 6.02 x 10²³ any time you want to refer to a large number of things.

The Periodic Table is handy when you want to convert between grams and moles - the relative atomic mass of each atom is numerically equivalent to the mass (in grams) of 6.02 x 10²³ of that atom, or in other words, 1 mole of that atom. So, 1 mole of Carbon-12 is 12 grams (found by looking at the relative atomic mass of Carbon on the Periodic Table).  1 mole of Nitrogen-14 is 14 grams.

Here's a slightly different example, what would 1 mole of H₂0 be in grams? Well, that would be the relative atomic mass of Oxygen plus the relative atomic mass of two Hydrogens -> 16 + 1 + 1 = 18 grams. So in 18 grams of H20, there will be 6.02 x 10²³ H20 molecules.

Does that make sense?