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How to read this equation

  1. Apr 13, 2012 #1
    Just having trouble determining what they mean by "The charge to mass ratio for a singly ionized benzene molecule is e/(78u)=1235712.07908557C/kg."


    For this, what would be the charge and what would be the mass?
     
  2. jcsd
  3. Apr 13, 2012 #2

    gneill

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    Staff: Mentor

    The single charge is a fundamental charge (equal to that on a proton, since 'singly ionized' means that the molecule has lost a single electron). The mass unit is an amu: atomic mass unit, also known as a dalton. Equivalent to 1.660538921 x 10-27 kg.
     
  4. Apr 13, 2012 #3
    I see. So to clarify q = 1.602 x 10-19 & m = 78*u = 1.295 x 10-25?
     
  5. Apr 13, 2012 #4

    gneill

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    Staff: Mentor

    Those are the numbers.
     
  6. Apr 13, 2012 #5
    But where does that large given number come in?
     
  7. Apr 13, 2012 #6

    gneill

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    Staff: Mentor

    I have no more information than what you stated in the first post. Where did you get the number, and in what context?
     
  8. Apr 13, 2012 #7
    Ah well I figured it out, what they mean is e/m = charge to mass ratio. The context doesn't add much to figuring out what it means however, it just sets up the question.

    As in every time e/m is encountered for the rest of the question, 1.26 x 106 (the long number of C/kg units) would be its value, which makes sense since it is asking for charge over mass. Kind of tricky too though...

    I had initially thought we needed to find the individual values of q and m, which is why I asked where the large number came into play. Thanks for the info about amu though!
     
    Last edited: Apr 13, 2012
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