Chemistry 3719 Chapter 2.txt

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Chemistry 3719 Chapter 2.txt
2012-02-03 20:39:58

O Chem
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  1. Why do low molecular weight alkanes have such low boiling points?
    Only weak intermolecular van der Waal forces attract the molecules to each other; these forces are easily broken at low temperatures
  2. How many isomers of C6H14 are possible?
    • 5 total
  3. What prefixes are used to describe alkane derivatives with alkyl chains of 8, 9, and 12 carbons?
    8 = oct; 9 = non; 12 = dodec
  4. Why is the name 5-methylhexane incorrect?
    The CH3 (methyl) group would be at C-2 following the IUPAC rules, i.e. 2-methylhexane

  5. How many isomeric butyl substituents are possible?
    Four: n-butyl; sec-butyl; isobutyl; t-butyl

  6. Give an alternate name for t-butylcycloheptane using the IUPAC form for the substituent

  7. Why do branched alkanes typically have lower boiling points than their unbranched isomers?
    The branched substituents get in the way of the alkyl chains interacting and being attracted; less intermolecular interaction leads to a lower boiling point
  8. Why do alkanes not dissolve in water?
    They are incompatible and do not attract; water is very polar, alkanes are very non-polar
  9. What oxidation numbers would you assign to the C atoms in CH3CH3, H2C=O, CH3Cl, and O=C=O?
    • -3 in CH3CH3
    • 0 in H2C=O
    • -2 in CH3Cl
    • +4 in CO2
  10. What type of valence orbitals are used by C in H2C=CH2 to form bonds?
    C will use sp2 orbitals for sigma bonds and a p orbital for the pi bond
  11. What are the expected bond angles around each C atom in CH3CH=CH2?
    109.5o around the C atom in CH3; 120o around the two C atoms in the double bond
  12. Provide the IUPAC name for CH3CH2CH2CH(CH3)CH(CH3)CH2CH3
  13. Give the generic formula for an alkane
  14. Which would have the higher boiling point, heptane or 2-methylhexane?
    Heptane; linear alkane with no branching interrupting intermolecular attractions
  15. Give an alternate name for the isopropyl substituent
  16. What is wrong with the name 2-methyl-3-ethylnonane?
    The ethyl should go before the methyl to keep the substituents correctly alphabetized
  17. Give the generic molecular formula for a cycloalkane
  18. What products are formed when any alkane is combusted?
    CO2 and H2O
  19. Which molecule contains the most highly oxidized C atom, CH4, CH3OH, or CO2?
    CO2 (+4)
  20. Which molecules contain the most unsaturation, alkenes, alkynes, or alkanes?
    Alkynes (2 pi bonds)