Question

A deuteron contains a proton and a neutron and has a mass of 2.013553 u. Calculate the mass defect for it in u and its energy equivalence in MeV.

(m_p = 1.007277 u, m_n = 1.008665 u, 1u = 931.5 MeV/c²)

Answer 1

The mass defect Δm is the difference between the total mass of the individual nucleons and the mass of the deuteron:

Δm = `(m_p + m_n) - m_"deuteron"`

= (1.007277 + 1.008665) − 2.013553

= 2.015942 − 2.013553

= 0.002389 u

E = Δmc²

= 0.002389 × 931.5 MeV/c²

= 2.220 MeV