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Homework Help: Energy released in fusion

  1. Oct 26, 2014 #1
    1. The problem statement, all variables and given/known data
    Two 2_1 H atoms undergo fusion to form 3_1 H and 1_1 H atom
    calculate the energy released by 1.0kg of deuterium..
    the amu is given as :2_1 H : 2.01402u
    3_1 H : 3.016049u
    1_1 H : 1.007825 u
    P/s : i am sure that the energy produced is 3.89MeV ....


    2. Relevant equations


    3. The attempt at a solution
    0.5 x (1000/2) x 6.02x10^23 x 3.89MeV = 5.85x10^26 MeV

    Is my working correct?
     
  2. jcsd
  3. Oct 26, 2014 #2

    haruspex

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    Why both the 0.5 and the /2?
    I get exactly double your answer by calculating the fraction of mass lost, then the total mass lost, then using E=mc2.
     
  4. Oct 26, 2014 #3
    0.5 means there' re 2 H atom /2 means mrr 2g... I am calculating the energy released for 1 H atom...
     
  5. Oct 26, 2014 #4
    So I divide 2
     
  6. Oct 26, 2014 #5

    haruspex

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    Yes, but why twice (0.5, then /2)?
     
  7. Oct 26, 2014 #6
    Mrr is 2g. And there re 2 H atom sow I divide 2 twice
     
  8. Oct 26, 2014 #7

    haruspex

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    Sorry, you've lost me. What are Mrr and 2g in this context?
     
  9. Oct 27, 2014 #8
    molar mass of deuterium= 2g
     
    Last edited: Oct 27, 2014
  10. Oct 27, 2014 #9

    haruspex

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    Ah, OK. I didn't recognise it because you truncated it from the given 2.01402.
    I've found the mistake in my own working and now get almost the same as you do: 5.80E26.
     
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