A thermal neutron is captured by a nucleus leading to fission as shown: Given atomic…

PHYSICS · Multi-part · A Level · Physics · Nuclear physics · Nuclear physics

Problem

A thermal neutron is captured by a

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

nucleus leading to fission as shown:

^{235}_{92}\mathrm{U}+{}^1_0\mathrm{n}\;\longrightarrow\;{}^{141}_{56}\mathrm{Ba}+{}^{92}_{36}\mathrm{Kr}+3\;{}^1_0\mathrm{n}

Given atomic masses (in u):

^{235}_{92}\mathrm{U}=235.043924

^{141}_{56}\mathrm{Ba}=140.914411

^{92}_{36}\mathrm{Kr}=91.926156

, neutron

=1.008665

. Use

1\,\text{u}=931.5\,\text{MeV}/c^2

and

1\,\text{MeV}=1.6\times10^{-13}\,\text{J}

. Answer the following. (i) Calculate the total rest mass of the products and of the reactants in atomic mass units. (ii) Determine the Q-value of the fission reaction in MeV. (iii) Convert the energy obtained in part (ii) to joules. (iv) How much energy is released when

1.0\,\text{kg}

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

completely undergoes this fission reaction? (Avogadro number

N_A =6.02\times10^{23}\,\text{mol}^{-1}

Related theory

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