Chemistry 3719 Chapter 2

  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
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  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

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

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

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  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)
Card Set
Chemistry 3719 Chapter 2
Chemistry 3719