Todays goals:

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Todays goals

• Moles
• Molecules

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(No Transcript)
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Admin stuff

• OWL Due Thur., Mon.
• Req. book probs. For Mon Ch. 3 35-40
• (bring answers to class)
• Reading Todays lecture 2.5, 3.5, 4.1
• 11.1-2
• Fridays lecture 3.6, 4.2
• 11.1-2
• For test 1 Ch. 1, Ch. 2
• 3.5-3.6
• 4.1-4.6
• Ch. 11

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Many MoleculesMeeting the mole
www.moleday.org
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Introducing the mole

• A dozen is a special number (12)
• Avogadros number is a special number (6.02214155
  x 1023) which happens to be a little bigger than
  a dozen
• Avogadros number is abbreviated NA
• Avogadros number has a chemical origin it is
  the number of atoms in
• 12 grams of carbon-12
• One mole of a substance consists of 6.02 x 1023
  particles of that substance
• Avogadros number is a conversion factor between
  atoms and moles
• (but not just between atoms and moles)

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Moles -gt atoms

• How many atoms are in 7.45 mmol of Cu?

4.49 x 1021 atoms
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Molar masses (moles ? grams)

• How much does one mole of Copper weigh (in
  grams)?
• We know that one atom of Cu weighs 63.546 amu
  (from the periodic table, and from mass
  spectrometer data).

• Conversion ones
• 1 atom Cu 63.546 amu
• 1 amu 1.6605439 x 10-24 g
• 1 mole Cu 6.02214155 x 1023 atoms Cu

Copper has a molar mass of 63.546 g / mol ?
Note units of g/mol
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SAT analogy

• A atommolecule
• B massgram
• amuatom C grammole
• D moleculeatom
• E NAmole

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Molar masses are conversion factors

• Used for two types of conversions
• Grams --gt moles
• Moles --gt grams

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Moles -gt grams

• How much does 0.21 mole of helium (He) weigh?

0.84 grams
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Grams -gt moles

• How many moles are in 3.92 g of germanium (Ge)

0.0540 moles
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Grams -gt atoms

• How many atoms are in 48.1 grams of silver (Ag)?

2.69 x 1023 atoms
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exercise 2.15 on ChemNow CD (version 6)

• PRS quiz

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MoleculesPutting atoms together
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How many atoms are present in these molecules?
(Chemical formula)
3 carbons 8 hydrogens C3H8
1 carbon 4 hydrogens CH4
2 carbons 6 hydrogens C2H6
4 carbons 10 hydrogens C4H10
molecular formula
structural formula
molecular structure
condensed molecular formula
CH4
CH3 CH3
CH3 CH2 CH3
CH3 CH2CH2 CH3