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#1 FrozenSnake  Icon User is offline

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Calculate the energy released per decay in a alpha emitter.

Posted 06 May 2011 - 05:48 AM

This is a physics question

Nuclide Pu is a alpha emitter. Pu(A) = 239, Pu(Z) = 94
a) Write the formula for the decay and calculate the energy per decay.

I have the formula done
Pu -> U + He | U(A) = 235, U(Z) = 92 , He(A) = 4, He(Z) = 2

Now I have to sum up the nuclide masses for He-4 and U-235 which is
4.002603u + 235.0439u = 239.0465u.

Now I am stuck, according to my solution booklet I should do this:
239.0522u (the Pu) - 239.0439 (where do this value come from?) = 0.0057u

Even if I put this 239.0522u - 239.0439u in my calculator I do not get 0.0057u I get 0.0083.
So where did 239.0439u and 0.0057 came from? I have read in the book on the chapter about this but it still doesn't makes any sense to me :(

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Replies To: Calculate the energy released per decay in a alpha emitter.

#2 Brewer  Icon User is offline

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Re: Calculate the energy released per decay in a alpha emitter.

Posted 07 May 2011 - 05:10 AM

While I'm sure that there are some more-than-competent physicists here at DIC, your question has gone unanswered in 24 hours so I'll suggest two other websites that will probably be more helpful for such a question.

PhysicsForums is a good place with some very smart people. While I've never asked a Physics question I have had some very helpful conversations in the Math forum and I can only assume that the gravity people will be just as accommodating.

Physics - Stack Exchange is another website that I'm not very familiar with but it is on the Stack Exchange network which is generally pretty helpful.

Hope this helped!
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#3 JackOfAllTrades  Icon User is offline

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Re: Calculate the energy released per decay in a alpha emitter.

Posted 07 May 2011 - 12:11 PM

239.0522u (the Pu) - 239.0439 (where do this value come from?) = 0.0057u

The 239.0439 looks like an error on the part of the book. If you plug in the sum of the nuclide masses, 239.0465, the difference is as the book says.
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