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Binding Energy for Hydrogen

  1. Sep 8, 2009 #1
    1. The problem statement, all variables and given/known data
    Find the binding energy for hydrogen in kJ/mol through positron emission.

    4(11H) → 42He + 2(0+1ß)


    2. Relevant equations
    E=Δmc2
    Mass of Hydrogen: 1.0079 amu
    Mass of Helium: 4.0026 amu
    1 amu = 1.6605 x 10-27kg


    3. The attempt at a solution
    Here is what I did:

    Eb= ((number of protons)xmass hydrogen)-mass of helium)*1.6605x10-27kg/amu)*c^2
    Eb = ((4*1.0079 - 4.0026) * 1.6605*10-27)*(2.998x108)2
    Eb= 4.33x10-12 kg m2/s2 = 4.33x10-12 J
    Eb = 4.33 x 10-15 kJ
    Eb = 4.33 x 10-15 * 6.022 x1023
    Eb = 2.61 x 109 kJ/mol
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 9, 2009 #2

    chemisttree

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    Science Advisor
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    Gold Member

    Haven't you neglected the mass of the 2 positrons?

    In the equation, E=Δmc2, the Δm = mass of reactants - mass of all products (including positrons)
     
  4. Sep 9, 2009 #3
    Isn't a positron basically massless considering it would just have the mass of an electron or will it make a big difference?
     
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