CHEM 240 003 SI Session

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CHEM 240 003SI Session 4Jan 15, 2009
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Objectives

• To master drawing and interpreting bond-line
  formulas.
• To understand the effects of intermolecular
  interactions on the boiling points and melting
  points of organic molecules.

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Quick Review

• What hybridization is associated with the
  following electron-domain geometries?
• Tetrahedral
• Trigonal planar
• Linear

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Quick Review

• Which intermolecular interaction arises from a
  temporary dipole?

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Quick Review

• Which intermolecular interaction arises between
  (N, O, or F) and (H-N, H-O, or H-F)?
• This is a stronger form of which other
  intermolecular interaction?

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Quick Review

• Is CO2 a polar or nonpolar molecule? Why?
• What is the hybridization of the carbon and
  oxygen atoms in this molecule?

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Quick Review

• A carboxylic acid involves a carbon double bonded
  to an oxygen and to a O-H group. Indicate the
  partial positive and partial negative charges on
  ethanoic acid (acetic acid).
• CH3COOH
• What is the hybridization of the carbon and
  oxygen atoms in this molecule?

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Practice Problems

• Convert the following structures from dash
  formulas to the corresponding bond-line formulas.
  (Ill draw them on the board)
• Propanoyl chloride
• 2-Butanone
• Propanal
• 1,3-Butadiene
• Cyclohex-2-enone
• Ethyl propanoate
• Acetic anhydride
• Diethyl ether

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Practice Problems

• Convert the following structures from bond-line
  formulas to the corresponding dash formulas.
  (Ill draw the structures on the board)
• Pentane
• Cyclohexane
• 3-Bromo-1-butyne
• 1-Bromo-2-pentanone
• Propane-1,2-diol
• 1,3-Cyclopentadiene
• Methyl propanoate
• 1-Bromo-3,3-diethyl-4-(1-methylethyl)heptane

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Practice Problems

• Which of the following would have a higher
  boiling point? Which intermolecular
  interaction(s) is (are) responsible for this?
  (Ill draw the structures)
• Ethane and Fluoroethane
• Methanol and Ethanol
• Formaldehyde and Methanol
• HCl and HI
• Ethane and Propane

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Questions?
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Closing Remarks

• Should be able to
• Draw and interpret bond-line formulas.
• Compare intermolecular interactions to determine
  relative boiling points/melting points.

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Next Session

• Monday at 1130