t Why stars Don\'t Make Lead Stars generate energy through nuclear fusion. A fus

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t Why stars Don't Make Lead Stars generate energy through nuclear fusion. A fusion reaction is exoergic (i.e., it gives off energy) if the product has a lower rest energy than the original nuclei. The binding en of a nucleus is defined as the difference between the rest energy that the individual particles would have if they were not bound in a nucleus a the rest energy of the nucleus itself. So, stated another way, fusion reactions are exoergic if the binding energy of the product is greater than the binding energy of the original nuclei Therefore, to calculate the binding energy of a nucleus, you will need to know the masses of a free proton and a free neutron. Normally, the mass of neutral hydrogen is used instead of the mass of a free proton. This substitution works because usually the mass of the product nucleus is given as the mass of the neutral atom with that nucleus, and so the energy related to electrons on each side of the equation should cancel. The relevant quantities are as follows: mass of neutral hydrogren H 1.007825 u mass of neutron 1.008665 u, and c2-931.5 MeV Part A The mass of neutral 16 15.994915 u. Find the binding energy for 16 Express your answer in millions of electron volts to four significant figures. binding energy for 16 MeV Submit Hints My Answers Give Up Review Part Part B Find the binding energy per nucleon for 16 Express your answer in millions of electron volts per nucleon to four significant figures. binding energy per nucleon for 127.6 MeV/nucleon 16 Submit My Answers Give Up incorrect; Try Again; 4 attempts remaining

Explanation / Answer

A)

mass defect = 8(1.007825 + 1.008665)) - 15.994915

binding energy = 931.5 MeV/amu x 0.137005 amu = 127.6201 MeV

B)

binding energy per nucleons = 127.6201MeV/16 nucleons = 7.9762 MeV/nucleons

C)

Mass of protons and neutrons = 26(1.007825u) + 30(1.008665u) = 56.4634u
Mass of Iron 56 = 55.934939u
Mass Defect = 56.4634 - 55.934939 = 0.528461 u
Binding Energy = 0.528461* 931.5 MeV = 492.2614Mev
Binding energy per nucleon = 492.2614 / 56 = 8.7903 MeV/nucleon

D)

Mass of protons and neutrons = 82(1.007825u) + 126(1.008665u) = 209.733444u
Mass of Pb = 207.976627 u
Mass Defect = 209.73344 - 207.976627 = 1.756813 u
Binding Energy = 1.756813* 931.5 MeV = 1636.4713Mev
Binding energy per nucleon = 1636.4713/208 = 7.8676MeV/nucleon-----ans

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