Binding energy calculation of a nucleus

[ellynx]

Hello,

I'd appreciate feedback on my calculation of binding energy, just wanted to check if I'm on the right track w/ regards to calculation steps (and thought process).

I'll try to be as clear as possible, please give me input if there's some notations / steps I should correct and keep in mind I have limited knowledge on the subject.

Homework Statement

Basically I want to calculate the binding energy per nucleus of the isotope ¹¹B in MeV.

Binding energy of the nucleus, which is the energy keeping the protons and neutrons together, thus the energy needed to break apart the "bonds" between the p+'s and n0's.
(in terms of force notation, would this be the strong nuclear force?)


Data given:

¹¹B: m = 11,0093 amu (Z = 5) (Z = # of p+ (I assume, since the # of p+ relates to the "iso" part of isotope))


mass/proton = 1,007276 amu
mass/neutron = 1,008665 amu

Homework Equations

∆m = (sum of protons and neutrons) - (measured mass of the isotope)

E=mC²

binding energy = ∆m·C²

The Attempt at a Solution

¹¹B ∑m = 5_p+ * 1,007275 amu + 6_n0 * 1,008665 amu = 11,08837 amu (the unbound system calculated mass)

¹¹B m = 11,0093 amu (measured somehow)


∆m = 11,08837 - 11,0093 = 0,07907 amu

Binding energy = 0,07907 amu * (3E8 m/s)^2 = 7,1163E15 J ( is it safe to say this is joules kg·m^2/s^2 ?) or do I need to convert amu's into Kg's first?

Assuming I get the result in J I continue to convert into MeV:

1 J = 6,24E18 eV = 6,24E12 MeV

MeV: 7,1163E15*J * 6,24E12 MeV/J = 4,44E28 MeV

This seems to me like a LOT of energy, how can I best evaluate my answer? Does this amount of energy seem like a reasonable amount? Can I relate it to the strong nuclear force?

Thanks.

 

[ellynx]

I looked up some binding energy values, and they all lay in quite a different interval. That value I got has to be horrendously off course.

Maybe I should divide by the atom number, but then again I would still get a pretty crazy value.

 

[nobahar]

I think you're more likely to get a response to this in the physics sections for homework questions (don't ask me where!). I don't think you can post the same question twice though, you may like to ask a moderator to transfer it, perhaps.

 

[Borek]

do I need to convert amu's into Kg's first?

Yes.

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