Question

Use the concepts of the strong nuclear force, binding energy and mass defect to briefly explain why a large amount of energy is given out during fission.

Answer 1

Solution:

Nuclear fission is a reaction in which a heavy nucleus is bombarded by high energetic neutrons, which causes it to split into two nuclei with equivalent size and magnitude, with the emission of two or three neutrons.

The binding energy is the energy required to split a nucleus of an atom into its component parts: protons and neutrons, or, collectively, the nucleons. The binding energy of nuclei is always a positive number.

The mass defect of a nucleus represents the mass of the energy binding the nucleus, and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed. The mass defect (Δm) is the difference of masses m2 and m1 as :

Δm = m2-m1

The actual mass (m1) which is always less than the sum of the individual masses of the constituent protons and neutrons (m2) because energy is removed when the nucleus is formed.

Binding energy (E) and mass defects (Δm) are related as:

E = Δm c²

Here, c is the speed of light.

Once mass defect is known, nuclear binding energy can be calculated by converting that mass to energy by using E = Δmc2

Thus, the higher mass defect (Δm) causes large binding energy and large binding energy causes strong nuclear forces of attraction, therefore, large amount of energy is given out during fission.