Moles What you're about to learn has nothing to do with little mammals or skin discoloration. A mole is a number... an awfully big number.

Once upon a time, a man names Avogadro (not avocado) figured out something that was brilliant. He figured out how many hydrogen atoms there are in a gram of hydrogen gas. (I am not sure how he did it - he couldn't have counted them individually.) There are approximately...
6.022 x 10²³ ... atoms in one gram. Then, if you have that many helium atoms, it would weigh about 4 grams. Lithium would weigh about 7 grams. In other words, one mole of an element would equal it's atomic weight in grams. What a useful concept!

Moles are written in scientific notation because hands begin to cramp writing (or typing) 602,200,000,000,000,000,000,000. That's how many molecules of water are in 18 grams of water. It's much easier to say 1 mole of water instead. It's easy to find out how much one mole of a substance weighs. For an element, like tantalum or bismuth, simply look at the atomic weight of the substance. For a molecule or mixture, just add the weights of the pieces together. For carbon dioxide, you have one carbon, with a weight of 12, and two oxygens, each with a weight of 16. By adding all the pieces together, you have 12 + 16 + 16. 44 grams of CO₂ is one mole.

A mole is such a huge number that it's tough to picture it. Try and imagine a mole of paperclips. It's tricky. Let's picture each of these clips weighing one gram. That is 6.02 x 10²³ grams of paperclips. Kilograms are easier to understand, so that would be 6.02 x 10²⁰ kilograms. Perhaps you're more used to pounds. Times 6.02 x 2.2 and you have 1.3244 x 10²¹ pounds. That's 6.622 x 10¹⁷ tons of paperclips! Let's stay scientific and look at that in metric tons, which is 6.02 x 10¹⁷ metric tons. We could make a whole continent out of that many paperclips!

Another comparison to understand how big a mole is would be to imagine soda cans. Imagine them covering the entire continental United States. Then, when you finish the first layer, you build another on top. If you had one mole of pop cans, how high would this stack reach? A mile? Fifteen? Try 13,000 miles in the air. Talk about cola wars!

While numbers like that are pretty hard to understand, they're terribly useful in chemistry. A formula may call for a mole of sodium to be mixed with a mole of chlorine. Rather than counting out numbers, you can be assured that 23 grams of sodium will mix with about 35.5 grams of chlorine evenly without a bunch of leftover molecules.

Scientists also use moles to make solutions. Often it's useful to know how concentrated a substance is. Rather than using percentage, scientists will use mole ratios. They compare the moles of the dissolved substance (solute) to the liters of the solvent. If you have 58.5 grams of NaCl, you have one mole. If you dissolve that in water until you have 1 liter, you have a 1 molar solution of salt. This is abbreviated as 1 mol/liter or 1 M.

Molarity =	moles of solute
	Liters of Solution

In case you're wondering, Chemistry geeks often celebrate MOLE DAY! This is held every October 23rd from 6:02 a.m. until 6:02 p.m. (6.02 x 10²³ - clever, eh?) So, this mole day, pour yourself a mole of your favorite drink, get together with your chemistry buddies, sing a song to Avogadro and his magic mole and pop in a video. I suggest Groundhog Day.