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Homework Help: Quantum Theory Conversion

  1. Sep 25, 2013 #1
    1. The problem statement, all variables and given/known data

    Calculate the size of the quantum involved in the excitation of a molecular vibration of period 20 fs. Express the results in joules and kilojoules per mole.

    2. Relevant equations

    ΔE = h/t

    3. The attempt at a solution
    I converted fs to seconds and used the above equation to figure out the answer in terms of joules, no problem. I have checked my answer for this, so I know it is correct. I also know what the answer is in terms of kilojoules per mole, but I can't for the life of me figure out exactly how to convert between the two. It doesn't seem as though I'm given enough information in the problem to do this conversion. I assumed that I would need to use the fact that 1000J=1kJ, but that doesn't seem to match up with the answer sheet that I was given.
    Last edited: Sep 25, 2013
  2. jcsd
  3. Sep 25, 2013 #2


    User Avatar

    Staff: Mentor

    You know energy required to excite one molecule. How many molecules in a mole?
  4. Sep 25, 2013 #3
    That was so simple! Thanks!
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