17 Apr
2011
17 Apr
'11
11:29 a.m.
I think the mole is defined from the number of attons
in a certain mass
of a certain isotope of an certain element (carbon 12 IIRC)
The mole is the amount of a substance which contains Avogadro's number
(6.0225 ? 10^23 ) of atoms or molecules of the substance.
Stated differently, it is the same amount of grammes of the substance as
that element's molecular weight.
The definition says that it is the amount of a substance which contains
the same number of molecules of the substance as 12 grammes of
carbon-12, which is a way of expressing the number of molecules in such
a manner that the required number of molecules can be provided by means
of weighing, which involves a comparison :-)
I suppose Tony's teacher would have wanted him to measure out a mole of
sugar by counting the number of molecules of sugar...
/Jonas