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Homework Help: What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614 x 1

  1. Dec 12, 2009 #1
    1. The problem statement, all variables and given/known data

    What is the energy (in kJ/mol) of infrared radiation that has a frequency of 1.614 x 107 MHz?

    2. Relevant equations

    E = nhv

    3. The attempt at a solution

    3 x 6.63 x 10^-34 (J x s) multiplied by 1.614 x 10^7 (MHz) multiplied by (10^6 Hz/1 MHz) multiplied by (1 kJ/ 1000J) = 3.210246 x 10^-20, which is wrong.
     
    Last edited: Dec 12, 2009
  2. jcsd
  3. Dec 12, 2009 #2
    Re: What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614

    E = hv
    v=1.614x10^13 hz
    h = 6.63x10^-34
    E = 1.07x10^-20 J
    E/1000 = kJ
    E = 1.07x10^-23 kJ
    per mole
    1.07x10^-23 * (6.02 x 10^23 atoms/mol)
    E = 6.44 kJ/mol

    hope that is clear, any questions lemme know :)
     
  4. Dec 12, 2009 #3
    Re: What is the energy (in kJ/mol) of infared radiation that has a frequency of 1.614

    Yes that's the right answer! But I'm still having trouble understanding why, in terms of units, you can multiply the last step by (6.02 x 10^23 atoms/mol) and still get units of (kJ/mol). When did the unit of "atoms" appear?

    Reflection: I made the mistake of not properly converting the Si-Units of "Mega-x" to "x" and neglected the aspect of moles.
     
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