How many is that? Does it matter? It's enough!
Since a mole is enough particles to make a formula mass, in g, if I take 22.99 g of Na I will have enough atoms to make a mole. If I take 18.02 g of water I will have enough molecules to make a mole. If I take 78.01 g of Al(OH)3 I will have enough formula units to make a mole. The nifty thing is, because of the way chemists have defined atomic (or formula, or molecular) mass, enough is always the same number! It has to be, because the atomic masses were calculated relative to each other using the idea that we could compare equal numbers of particles.
Actually, the "enough" is known and is equal to 6.02 x 1023, which isn't just a big number, it's an enormous number! In fact, if molecules of water were as thick as a penny, about 1 millimetre, a mole high stack of pennies would be 63,000 light years high! Yet that is the number of molecules in just 18 g of water.
Remember that atomic masses are actually calculated relative to carbon-12? So if we had exactly 12 g of carbon-12, we'd also have enough atoms to make a mole. If fact, that is the way the mole is currently defined.
Copyright © 1998 - 2008 David Dice