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Barrier To Rotation quiz

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  • The backbone of a polypeptide chain is flexible due to rotation around which bond(s)?
    The flexibility of a polypeptide chain is due to rotation around the single bonds between the alpha carbon and the amide nitrogen, and between the alpha carbon and the carbonyl carbon.
  • What is the energy cost for rotation when two methyl groups are perfectly eclipsed?
    The energy cost for rotation when two methyl groups are perfectly eclipsed is 11 kilojoules per mole.
  • How much energy does it cost for an eclipsed interaction between a methyl group and a hydrogen atom?
    An eclipsed interaction between a methyl group and a hydrogen atom costs 6 kilojoules per mole.
  • What is the energy cost for an eclipsed interaction between two hydrogen atoms?
    The energy cost for an eclipsed interaction between two hydrogen atoms is 4 kilojoules per mole.
  • What is the energy cost for a gauche interaction between two methyl groups?
    The energy cost for a gauche interaction between two methyl groups is 3.8 kilojoules per mole.
  • Why is the energy cost for a methyl-methyl gauche interaction nearly equivalent to an eclipsed hydrogen interaction?
    The energy cost for a methyl-methyl gauche interaction is nearly equivalent to an eclipsed hydrogen interaction because the large methyl groups are staggered but still interact significantly.
  • What is the least energetic conformation in molecular rotation?
    The least energetic conformation in molecular rotation is the anti conformation.
  • What is the most energetic conformation in molecular rotation?
    The most energetic conformation in molecular rotation is the eclipsed conformation.
  • Why is it important to memorize common energy values related to molecular rotation barriers?
    Memorizing common energy values helps predict the likelihood of molecular rotations and the stability of different conformations.
  • What does the term 'energy cost' refer to in the context of molecular rotation?
    The term 'energy cost' refers to the amount of energy required to rotate bonds into a specific conformation, such as eclipsed or gauche.