Question
Explain the phenomenon of nuclear fission.
✓
Answer
→When a heavy nucleus is bombarded with a neutron, then first neutron is absorbed. This nucleus is in a highly excited state. As a result, it splits into two lighter nuclei of approximately equal mass to become stable.
→Neutron is chargeless so it does not have to face coulomb forces. So neutron is a best projectile.
→When a neutron is bombarded on the nucleus of uranium its nucleus breaks into two almost equal parts. Its nuclear reaction is as below :
$\begin{array}{l}
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{56}^{144} B a+{ }_{36}^{89} K r+3\left({ }_0^1 n\right)+ Q \\
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{51}^{133} S b+{ }_{41}^{99} N b+4\left({ }_0^1 n\right)+ Q \\
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{54}^{140} Xe +{ }_{38}^{94} S r+2\left({ }_0^1 n\right)+ Q
\end{array}$
→The fission fragments are radioactive and by successive emmision of $\beta$-particles results in the stable nuclei.
→During the fission process of uranium the energy released per fission is almost 200 MeV .
→Suppose a nucleus with mass number $A =240$ breaks into two fragments each of $A =120$.
→Binding energy per nucleon for a nucleus with $A =240$ is 7.6 MeV and for a nucleus with $A =120$ is 8.5 MeV .
→Gain in binding energy per nucleon
$\begin{array}{l}
=8.5-7.6 \\
=0.9 MeV
\end{array}$
→Total gain in binding energy
$\begin{array}{l}
=0.9 \times 240 \\
=216 MeV .
\end{array}$
→The disintegration energy in fission events first appears as the kinetic energy of the fragments and neutrons. Eventually it is transferred to the surrounding matter appearing as heat.
→In a nuclear reactor this process takes place in a controlled manner whereas in an atomic bomb this process takes place in an uncontrolled manner.
→Neutron is chargeless so it does not have to face coulomb forces. So neutron is a best projectile.
→When a neutron is bombarded on the nucleus of uranium its nucleus breaks into two almost equal parts. Its nuclear reaction is as below :
$\begin{array}{l}
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{56}^{144} B a+{ }_{36}^{89} K r+3\left({ }_0^1 n\right)+ Q \\
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{51}^{133} S b+{ }_{41}^{99} N b+4\left({ }_0^1 n\right)+ Q \\
{ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{54}^{140} Xe +{ }_{38}^{94} S r+2\left({ }_0^1 n\right)+ Q
\end{array}$
→The fission fragments are radioactive and by successive emmision of $\beta$-particles results in the stable nuclei.
→During the fission process of uranium the energy released per fission is almost 200 MeV .
→Suppose a nucleus with mass number $A =240$ breaks into two fragments each of $A =120$.
→Binding energy per nucleon for a nucleus with $A =240$ is 7.6 MeV and for a nucleus with $A =120$ is 8.5 MeV .
→Gain in binding energy per nucleon
$\begin{array}{l}
=8.5-7.6 \\
=0.9 MeV
\end{array}$
→Total gain in binding energy
$\begin{array}{l}
=0.9 \times 240 \\
=216 MeV .
\end{array}$
→The disintegration energy in fission events first appears as the kinetic energy of the fragments and neutrons. Eventually it is transferred to the surrounding matter appearing as heat.
→In a nuclear reactor this process takes place in a controlled manner whereas in an atomic bomb this process takes place in an uncontrolled manner.
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