nuclear decay?

Question

complete data of question:
a nitrogen nucleus N(A=14,Z=7) bombared with an alpha particle of a certain energy transmutes to an oxygen nucleus(A=17,Z=8) and a proton
a:write a equation for this nuclear reaction
b:find the minimum energy of alpha particle to make this reactin occur
(mass of nitrogen=2.32530*10^-26kg,mass of oxygen=2.82282*10^-26kg,mass of proton=0.16735*10^-26kg and mass of alpha particle=0.66466*10^-26kg)
attempt on this questin:
i have written the reaction
in second part we have to calculate mas defect for finding its energy by e=mc^2
in fission reaction i learnt that mass of reaction will always be greater than product,but here by calculation mass of product is greater ,why is this so.and plz tell me why energy equivalent to mass defect is always alpha particle energy why not other elements like nitrogen and oxygen
answer of this question is1.89*10^-13j,i have calculated this answer but that comes in negative as i subtracted reactants minus product

Answer 1

This is a nuclear reaction: it is not nuclear decay as such. In any case fission is only exothermic for nuclei more massive than iron.

In this case, because the mass of the products is greater than the mass of the reactants, the energy that has to be supplied in order for the reaction to take place is the (kinetic) energy of the alpha particle.

The question is asking for the minimum energy of the alpha particle. For a reaction to occur at this energy the nitrogen nucleus will have to be moving towards the alpha particle so that the total momentum is zero. It seems that the question is a simplified picture. If the alpha particle were colliding with a nitrogen nucleus that was initially stationary, then the alpha particle would have to have more energy as some of its momentum would be transferred to the nitrogen nucleus.

I haven't checked your calculation but if you obtained the answer from the mass defect it is likely that the energy you have calculated is the kinetic energy of the alpha particle rather than the total energy, which includes its mass energy. What you've calculated is the energy required to make the reaction occur. It could be provided, in part, by the alpha particle or by the nitrogen atom. Strictly speaking for the reaction to occur at this energy the two particles should be moving towards each other such that all their kinetic energy will be converted into mass energy.

I think the question you have answered is a simplification. My first two paragraphs should answer most of your question.

Answer 2

I'm interested in this too, but not sure if I'm way off track here, but wouldn't the loss of mass after the rxn be directly proportional to the energy given off? Since ... E = M C^2
[1.89 x 10^-13j] / [ C^2] = Mass (am I right so far?)
And if you have an initial value and you subtract a value which is less than the product you should get a positive answer, so if you are getting negative answers then your second value must be greater than initial value. Or, you might have to use an abosulte value symbol to force the postive answer. Or you're reading the question wrong from your text book. But, all of my ideas are just guesses, so if I was of no help, maybe just reading my silly stuff might help you figure out your error.

Answer 3

Ahh. I see what you did.

You've done a nuclear fusion reaction rather than a nuclear fission one.

The energy of the alpha particle will need to be sufficient to overcome the coulomb force of repulsion of the +7e of the nitrogen and the +2e of the alpha particle. Once they get within about 10^-15m, they will combine thanks to the strong nuclear force.

0.5mv^2= Qn.Qa/.pi.Eo.r

where m = mass of alpha particle
Qn = charge of nitrogen nucleus , 7e
Qa = charge on alpha particle , 2e
e = 1.6x10^-19C
pi= 3.1416
r = 10^-15m
Eo= permitivity of free space. I forget the value, 8.85x10^? [12, i think]

Anyway. In fission, what you have is a big thing that becomes smaller things with less rest mass

In fusion you take two small things and make a bigger one with less rest mass.

and the mass defect is converted to E=m...you know

The transition from Fusion releasing energy to fission releasing energy occurs at iron. Smaller than iron, fusion. Larger, fission.

Answer 4

which assertion is real approximately nuclear decay? a). Nuclear decay costs are tormented by the temperature of a pattern b). Nuclear decay costs are tormented by the exterior area of a pattern ==> c). Nuclear decay costs are consistent d). Nuclear decay costs are tormented by atmospheric tension -------------------------------------- "between the paradigms of nuclear technological understanding because of the fact the very early days of its learn has been the final information that the 0.5-existence, or decay consistent, of a radioactive substance is self sufficient of extra advantageous-nuclear issues." --------------- i'm hoping it particularly is robust.

Answer 5

I'll get back to you when I've completed my post-grad degree in nuclear physics...