How many atoms are in 1.75 moles of zinc?

1 Answer
Jun 2, 2016

Answer:

How many atoms in #1.5# #"dozen"# zinc atoms? Clearly, there are #18#.

Explanation:

We know that #1# #mol# of stuff specifies #"Avogadro's Number, "N_A# individual items of stuff. Avogadro's Number #=# #6.022xx10^23*mol^-1#.

So you have #1.75xxN_A# atoms of zinc. You do the arithmetic, and tell us what is the mass of this quantity, this number, of zinc atoms?

The use of #"Avogadro's number"# as we use any other collective number, e.g. score, dozen, gross, is entirely legitimate. Why do use such an absurdly large number? It turns out that #N_A# #""^1H# atoms have a mass of #1*g# precisely. #"Avogadro's number"# is thus the link between atoms and molecules, the which we can't see, to the macro world of grams and litres, that which we can conveniently measure in the laboratory.