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Energy Change Nuclear Chemistry

  1. Nov 19, 2016 #1
    1. The problem statement, all variables and given/known data
    Determine the energy change, delta E, in J when 500 g of 229/90 Th undergoes the following nuclear reaction:
    229/90 Th --> 225/88 Ra + 4/2 He
    The nuclear masses in amu or g/mol are: Th-229: 229.03175; Ra-225: 225.02360; He-4: 4.00260

    2. Relevant equations
    delta E = deltam(c)^2
    c= 3*10^8
    1 g= 6.02*10^23

    3. The attempt at a solution
    I know how to do a problem like this without a different mass input, but I have no idea how to incorporate the 500 grams into the solution. The answer is -1.09*10^12 J
     
  2. jcsd
  3. Nov 19, 2016 #2

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    Step at a time: how many mol?
     
  4. Nov 19, 2016 #3
    Would you do 500 g Th * 1 mol Th/229.03175 g Th = 2.183 mol Th
     
  5. Nov 19, 2016 #4

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    Yes. Can you take it the rest of the way?
     
  6. Nov 19, 2016 #5
    Well I don't really know what to do with that number now. How do I incorporate it into the change in mass?
     
  7. Nov 19, 2016 #6

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    229 = 225 + 4; what is the mass defect?
     
  8. Nov 19, 2016 #7
    The mass defect would be around -4, but so then how do you incorporate the 2.183 mol of Th??
     
  9. Nov 19, 2016 #8

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    "WORNG!" Try again, please.
     
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