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# Energy per nucleon of fuel - how to count - PLEASE HELP EXAM IN 1.5H! :( watch

1. I have some questions, one about fusion reactions, one about fission and one few extra questions.

Fusion:

6 2 4
Li + H ----> 2 He
3 1 2

It gives off approx. 22.4MeV

1)Then I have to find energy per nucleon fuel. Is only hydrogen fuel?
2)If only hydrogen is fuel what is Li then?

I assumed that everything that is needed for reaction is fuel and therefore there are 8 nucleons of fuel, as 6+2=8.

3) What if the reaction was between two hydrogen isotopes? 3H1 and 2H1? Are they both fuel?

4) How many nucleons of fuel are present in above case? (q3)

Fission

Energy released in fission of one Uranium-235 nucleus is approx. 200 MeV. What is the energy per nucleon?

There are 235 nucleons in one U-235 nucleus so surely it is 200MeV/235? But the answer sheet says otherwise... is this a misprint?

Extra questions

1. What is brief definition of nucleus?
2. What is brief definition of an atom?

Thank you! I will be very grateful for answers
2. You sure the answer sheet doesn't give it in Joules?
3. (Original post by lilangel890)
You sure the answer sheet doesn't give it in Joules?
Yes, I am sure. Do you know answers to any of my questions? 2.5h left
4. 1)Then I have to find energy per nucleon fuel. Is only hydrogen fuel?
I would assume, like you have, that anything that is consumed in the process is considered fuel. In the case of the reaction you describe, this would count both Li and H as fuel; so 8 nucleons would be the number I would also use.

3) What if the reaction was between two hydrogen isotopes? 3H1 and 2H1? Are they both fuel?
The criteria for being fuel would be (I assume) seeing if the atom has been used up in the fusion process, i.e. is it still around in its original form after fusion - if no, it was fuel.

4) How many nucleons of fuel are present in above case? (q3)
I don't know - what is the reaction in full (i.e. the products are what?)

There are 235 nucleons in one U-235 nucleus so surely it is 200MeV/235? But the answer sheet says otherwise... is this a misprint?
What does the answer sheet say?

1. What is brief definition of nucleus?
A nucleus is the positively charged core of an atom, consisting of protons and neutrons bound together by the strong nuclear force. It has a typical radius of the order of 10^-14m.

2. What is brief definition of an atom?
An atom consists of a positively charged core, containing both neutrons and protons, surrounded by a negatively charged cloud of orbiting electrons. The result is that the overall, atoms are electrically neutral. The typical radius of an atom is 10^-10m.

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