Section 3.1 The Mole and Molar Mass

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Section 3.1 The Mole and Molar Mass
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The Mole and Molar Mass

• In this section
• Connecting the atomic and real worlds
• The mole
• Elemental molar mass
• Compound molar mass
• Conversions between atoms, moles, and mass

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How do we relate atoms and molecules to the real
world?
1 mole of atoms or molecules fills a small
handful.
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1 mole 6.02 x 1023 atoms or molecules
1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl2?2H2O
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1 mole 6.02 x 1023 atoms or molecules
1 mole of elements Cu, Al, S,
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1 mole 6.02 x 1023 atoms or molecules
1 mole compounds K2Cr2O7, H2O and CuCl2?2H2O
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The mole as a conversion factor
1 mol element 6.02 x 1023 atoms of that element
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The mole as a conversion factor
1 mol element 6.02 x 1023 atoms of that element
moles atoms
1.95 mol Al
atoms moles
4.68 x 1023 Cu atoms
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The mole as a conversion factor
1 mol element 6.02 x 1023 atoms of that element
moles atoms
When doing these calculations, does it matter
which element is used?
atoms moles
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Elemental molar mass
elemental molar mass mass of 6.02 x 1023
atoms elemental molar mass atomic weight on
periodic table,
in grams per mole
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Molar mass
1 mol Al 1 mol F
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Molar mass as a conversion factor
1 mol Al molar mass Al 26.98 g Al
moles grams
1.95 mol Al
1.95 mol Al
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Molar mass as a conversion factor
1 mol Cu molar mass Cu 63.55 g Cu
grams moles
49.4 g Cu
49.4 g Cu
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Compound molar mass
compound molar mass mass of 6.02 x 1023
molecules compound molar mass sum of atomic
weights of atoms
in the molecule
SO2
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Converting between grams and moles for a compound
Step 1. Determine molar mass Step 2. Use molar
mass as a conversion factor
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Molar mass as a conversion factor
SO2 64.06 g/mol
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?
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Multistep Problems
How many oxygen atoms are present in a 212-g
sample of SO2?
Problem Map