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Homework Help: Molar binding energy of uranium-235 nuclei

  1. Nov 7, 2011 #1
    1. The problem statement, all variables and given/known data

    What is the molar binding energy of uranium 235 nuclei?
    Givem: The mass of 1 uranium nuecli is 235.0439u

    2. Relevant equations

    E=Δmc^2

    3. The attempt at a solution

    mass of nucleons: m=92P+143n=236.90814u

    mass of nucleus: m=234.99343u

    Δm=239.90814-234.99343u=1.9147u

    Emolar=(1.9147u)(3x10^8m/s)^2(1.67x10^-27kg/u)
    =2.8778x10^-10 J/nucleus (6.02x10^23 nuclei/mole)(1kJ/1000J)
    =1.7324x10^11 kJ/mol

    Is my answer correct? Also did I name the nucleons/nucleus correctly? I'm not sure if I should have called them what I called them since the nucleons are the nucleus technically.
     
  2. jcsd
  3. Nov 8, 2011 #2

    ehild

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    Homework Helper

    Nucleon is a collective name for the neutron and the proton. These are the two constituents of the atomic nucleus.
    I did not check your numbers, but the method looks correct, except you left out the Avogadro's number in the first line.

    ehild
     
  4. Nov 8, 2011 #3
    So what should I change the names to?

    And why do I need Avogadro's number in the first line?
     
  5. Nov 8, 2011 #4

    ehild

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    Homework Helper

    You used the correct name for protons and neutrons. They are nucleons.
    I quoted your first line for Emolar but it was the binding energy of one nucleus.

    ehild
     
  6. Nov 8, 2011 #5
    It is molar, I converted it to kJ/mol.
     
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