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Molar mass (Chapter 2.7 and 2.8)
1 dozen = 12 “things” or items
(1 dozen eggs = 12 eggs)
1 mole = 6.02214199 x 10
23
“things” or items
(1 mole eggs = 6.02214199 x 10
23
eggs)
Avogadro’s number, N
A
= 6.022 x10
23
items/mol
The mole unit connects the nanoscale (atoms,
molecules, etc.) to the macroscale (human
scale).
1 mole of copper atoms = 1 mol Cu
= 6.022 x 10
23
atoms Cu
≈
24 pennies
Molar mass
: the mass in grams of one mole of
any substance (elements or compounds).
Also known as atomic mass, atomic weight,
molecular weight (MW), and formula weight
(FW), but these terms can be misleading.
What is the molar mass (MM) of an element?
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View Full DocumentChemistry 101 Fall 2010
For carbon12 (
12
C), the molar mass is
1 mole
12
C = 6.022 x 10
23
atoms
12
C = 12 g
12
C.
12
C is defined to be exactly 12 g.
MM of
12
C = exactly 12 g/mol.
What is the MM of carbon from the periodic
table?
Isotope
Atomic mass (g)
Molar mass (g/mol)
Abundance
12
C
1.992646 x 10
23
12 (exactly)
98.93%
13
C
2.15928 x 10
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 Fall '11
 ScottNickolaisen
 Chemistry, Mole

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