Question

In fission of one uranium-235 nucleus, the loss in mass is 0.2 a.m.u Calculate the energy released.

Answer 1

Atomic mass unit (a.m.u ) is a unit of mass used to express mass of atomic particles. One atomic mass unit ( 1 a.m.u )is defined as one twelfth $1/12$ of the mass of an atom of carbon-12.

1 a.m.u .=$1.66\times {10}^{-27}kg$
Relation between a.m.u. and MeV
According to Einstein's mass-energy equivalence relation,
$E=\left(\Delta m\right)c^2$
So, we need to find energy equivalent of 1 a.m.u $\begin{array}{cc}E& =(0.2\times 1.66\times {10}^{-27}kg)\times {(3\times {10}^8{ms}^{-1})}^2\\ & =2.98\times {10}^{-11}\text{joules}\end{array}$
We know 1 MeV $=1.6\times {10}^{-13}J$
$E=\frac{2.98\times {10}^{-11}}{1.6\times {10}^{-13}}MeV=186.25MeV$

Final answer: Thus, $186.25MeV$ of energy is released when the loss in mass is 0.2 a.m.u .