A typical fission process of uranium-235 may be represented

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

Problem

A typical fission process of uranium-235 may be represented, in a simplified form, by

^{235}_{\;92}\text{U} + ^{1}_{0}\text{n} \rightarrow ^{141}_{\;56}\text{Ba} + ^{92}_{\;36}\text{Kr} + 3\,^{1}_{0}\text{n}

Atomic masses:

^{235}\text{U} = 235.043929\,\text{u}

^{141}\text{Ba} = 140.914411\,\text{u}

^{92}\text{Kr} = 91.926156\,\text{u}

^{1}_{0}\text{n} = 1.008665\,\text{u}

. Take

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

. (i) Write the mass defect

\Delta m

for one fission event, showing all terms clearly. (ii) Calculate the energy released per fission event in MeV. (iii) Determine the total energy obtainable (in joule) if

1.0\,\text{kg}

^{235}\text{U}

undergoes complete fission. (Avogadro number

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

.) (iv) Coal releases roughly

3.0\times10^{7}\,\text{J}

per kilogram when burnt. Estimate how many kilograms of coal would be needed to release the same amount of energy as in part (iii).

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