A question about the mole?

Question

why is the counting unit (the mole) used so often in chem instead of a mass unit? I really don't understand.

Answer 1

because mole shows a certain number of molecules(6.022*10^23) and since molecules react with each other, this is the easiest unit to use. for example hydrogen reacts with oxygen in ratio 2:1 to form water, so if we have 1 mole of hydrogen, we'll need 0.5 mole of oxygen. but if we have 1 Gram of hydrogen, we need mush more than 1 Gram of oxygen.(approximately 8gr) so you can see it's easier to use mole instead of mass unit.

Answer 2

The mole relates directly to the number of atoms or molecules that are present. Specifically, one mole contains about 6x10^23 molecules/atoms. This is useful because, for example, water has the chemical formula H_20, so there are two hydrogen atoms for every oxygen atom. Thus, if you wanted to burn hydrogen to create water in such a way that there would be no hydrogen or oxygen left over, you would need to have twice as many moles of hydrogen as you do oxygen. If you were doing this by weight the 2:1 correspondence would not be so obvious, because a hydrogen atom weighs about 1/16 of an oxygen atom. It is not immediately apparent that about 1/8 as much hydrogen (by weight) as oxygen means that there are two atoms of hydrogen for very one atom of oxygen. Saying that there are twice as many moles of hydrogen which reacted as there were moles of oxygen that reacted makes this relation obvious.

Answer 3

Because the mole is a kind of mass unit: if you say that you used two moles of carbon dioxide, it is straightforward to convert that to a mass amount.

Answer 4

Because a mole always , **always** contains 6.02*10^23 atoms or molecules of whatever 'stuff' it is you're measuring.


Doug

Answer 5

a mole stays under...the number must be lower

Answer 6

check out Avagadro's number.