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mass
'no magic to the mole'
amount
molar mass
concentration
solution volume
gas volume
molar gas volume
Avogadro
constant, L
number of
entities, N
Now try the following question.
G8. THE MOLE IS NOT A COUNTING UNIT
As a consequence of the adoption in S.I. of the MOLE as the unit for the physical quantity ‘AMOUNT OF SUBSTANCE’, the ‘mole’ cannot correctly be used in the same sense as
a counting unit like ‘dozen'.
The ‘mole’ is NOT a counting unit:
it is the S.I. unit for the physical quantity known as ‘amount of substance’.
As Peter G. Nelson (Hull) has emphasised so correctly on several occasions:
it is legitimate to write
but incorrect to assert
One can write either
or
number of eggs = 3 doz = 36
number of molecules = 18.0
x
10
23
= 1.80
x
10
24
number of molecules = 3 mol = 18.0
x
10
23
amount of substance = 3 mol
Using the commonly encountered SI quantity symbols makes the situation clearer still:
N = 18.0
x
10
23