The isotope undergoes fission when it absorbs a thermal neutron as follows:

PHYSICS · Multi-part · CBSE · Physics · Nuclei · Nuclei

Problem

The isotope

^{235}_{92}\text{U}

undergoes fission when it absorbs a thermal neutron as follows:

^{235}_{92}\text{U} + n \rightarrow ^{141}_{56}\text{Ba} + ^{92}_{36}\text{Kr} + 3n

. Use the data given below to answer the questions. (i) Write an expression for the mass defect

\Delta m

for the above reaction. (ii) Using the atomic masses

m(^{235}_{92}\text{U}) = 235.0439\,\text{u}

m(n)=1.0087\,\text{u}

m(^{141}_{56}\text{Ba}) = 140.9144\,\text{u}

and

m(^{92}_{36}\text{Kr}) = 91.9262\,\text{u}

, calculate

\Delta m

in atomic mass units (u). (iii) Convert the mass defect obtained in part (ii) into energy released

Q

per fission in (a) MeV, and (b) joules. Take

1\,\text{u}=931.5\,\text{MeV}

and

1\,\text{eV}=1.6\times10^{-19}\,\text{J}

. (iv) Determine the percentage of the initial mass (total mass of reactants) that is converted into energy in this fission reaction.