Post on 13-Jan-2016
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Section 3.1 The Mole and Molar Mass
The Mole and Molar Mass
In this section…
a. Connecting the atomic and real worlds
b.The mole
c. Elemental molar mass
d.Compound molar mass
e.Conversions between atoms, moles, and mass
How do we relate atoms and molecules to the real world?
1 “mole” of atoms or molecules fills a small handful.
1 mole = 6.02 x 1023 atoms or molecules
1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl22H2O
1 mole = 6.02 x 1023 atoms or molecules
1 mole of elements Cu, Al, S,
1 mole = 6.02 x 1023 atoms or molecules
1 mole compounds K2Cr2O7, H2O and CuCl22H2O
The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element
The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element
moles atoms
atoms moles
1.95 mol Al
4.68 x 1023 Cu atoms
The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element
moles atoms
atoms moles
When doing these calculations,does it matter which elementis used?
Elemental molar masselemental molar mass = mass of 6.02 x 1023 atoms
elemental molar mass = atomic weight on periodic table, in grams per mole
Molar mass
1 mol Al =
1 mol F =
Molar mass as a conversion factor1 mol Al = molar mass Al = 26.98 g Al
moles grams
1.95 mol Al1.95 mol Al
Molar mass as a conversion factor1 mol Cu = molar mass Cu = 63.55 g Cu
grams moles
49.4 g Cu49.4 g Cu
Compound molar masscompound molar mass = mass of 6.02 x 1023 molecules
compound molar mass = sum of atomic weights of atoms in the molecule
SO2
Converting between grams and moles for a compound
Step 1. Determine molar massStep 2. Use molar mass as a conversion factor
Molar mass as a conversion factor
moles grams
What is the mass of a 1.45 mol sample of SO2?
grams moles
What amount, in moles, of SO2 does a 212-g sample represent?
SO2 = 64.06 g/mol
Multistep ProblemsHow many oxygen atoms are present in a 212-g sample of SO2?
Problem Map: