Question

What is the average binding energy per nucleon for Argon-40 (A=40, Z = 18) in MeV/nucleon? Note - keep 4 significant figures.

The answer is 8.595 but I'm not sure how to get to this answer.

Answer 1

m_e = mass of single electron = 0.0005486 amu

m_p = mass of single proton = 1.007276 amu

m_n = mass of single neutron = 1.008665 amu

M = mass of Argon = 39.9623831

mass defect is given as

m = [Z (m_e + m_p) + (A - Z) m_n] - M

m = [(18)( 0.0005486 + 1.007276) + (40 - 18)(1.008665)] - 39.9623831

m = 0.3691077

Binding energy per nucleon is given as

E = m (931.5)/A

E = (0.3691077) (931.5)/40

E = 8.595 MEV/nucleon