Question

a) Calculate BE/A (in MeV) for 12C. Stable and relatively tightly bound, this nuclide is most of natural carbon. (Assume 1 u = 931.5 MeV/c2. Give your answer to at least 2 decimal places.) Incorrect: Your answer is incorrect. MeV

(b) Calculate BE/A (in MeV) for 11C. Incorrect: Your answer is incorrect. MeV Is the difference in BE/A between 12C and 11C significant? One is stable and common, and the other is unstable and rare. (Assume the difference to be significant if the percent difference between the two values is greater than 5%.) Yes No

Answer 1

(a)

Mass of 12C = 12.00000 u

mass of proton = 1.007825 u

mass of neutron = 1.008665 u

12 C has 6 protons and 6 neutrons.

Binding energy, BE = mc^2

m = (6*1.007825 + 6*1.008665) - 12.0000

m = 0.09894 u

BE = 0.09894 *931.5 = 92.16

BE per nucleon, BE / A = 92.16 / 12

BE / A = 7.68 MeV

(b)

Mass of 11C = 11.0114336 u

11C has 6 protons and 5 neutrons.

m = (6*1.007825 + 5*1.008665) - 11.0114336

m = 0.07884 u

BE = 0.07884 *931.5 = 73.44 MeV

BE per nucleon, BE / A = 73.44 / 11

BE / A = 6.67 MeV