Best answer:
one ATOM of carbon is 12 amu
one MOLE of carbon is 12 grams
one mole is approx. 6.022*10^23 atoms
and the "rule" (which seems to work for all elements and molecules) is:
if you have that number of atoms, then the mass (in gram) is the same number as the number of amu in one atom (or molecule).
1 atom...
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Best answer: one ATOM of carbon is 12 amu
one MOLE of carbon is 12 grams
one mole is approx. 6.022*10^23 atoms
and the "rule" (which seems to work for all elements and molecules) is:
if you have that number of atoms, then the mass (in gram) is the same number as the number of amu in one atom (or molecule).
1 atom of Xenon is (on average) 131.293 amu
(in chemistry, we use the weighted average of all stable isotopes found in nature)
(Xenon has 8 stable isotopes, ranging from 124 amu to 136 amu)
If you get a mole of Xenon (6.022*10^23 atoms) with the same mix of isotopes as found in nature, then it will have a mass of 131.293 grams
If, on the other hand, you manage to get a mole of Xenon-129 (where all the atoms of Xenon each have 129 amu), then that mole will only have a mass of 129 grams.
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Because, in chemistry, we work with average masses most of the time, using the mole (where the set of 6.023*10^23 atoms will normally follow the same mixing ratios as found in nature) allows us to make better calculations to determine inputs and outputs (important for experiments and for industrial planning).
Balancing equations, for example
2H2 + O2 --> 2H2O
is supposed to involve atoms. But for determining quantities (mass), we have to work with moles... and we forget to point that out.
Therefore, we end up using words like "atom" when we mean mole.
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5 days ago