Q. 5.70 - An Introduction to General, Organic, and Biological Chemistry

Question

a. What are the products in the fission of uranium-$235$that make possible a nuclear chain reaction? $(5.6)$

b. What is the purpose of placing control rods among uranium samples in a nuclear reactor?

Step-by-Step Solution

Answer

Option a ia

          A chain reaction is the name for this process. 

Option b is

         To slow down the fission reaction, control rods are placed among uranium samples in a nuclear reactor.

Step1: Explanation of option a

     Fission is the splitting of a big nucleus into smaller parts. One or more forms of radiation, as well as a significant amount of energy, are released during this process.

     When uranium -$235$ collides with a neutron, it forms an unstable nucleus that splits into smaller nuclei like $Kr$ and $Ba$, along with a lot of energy and multiple neutrons. These high-energy neutrons strike the other $U-235$ nuclei, causing fission to proceed, resulting in more high-energy neutrons colliding with more $U-235$ nuclei. A chain reaction is the name for this process.

Step 2: The following is the fission process of Uranium- 235 :

$$\begin{gathered} {}_0{}^{1}n+{}_{92}{}^{215}\mathrm{U}\to {}_{ 92 \\ \mathrm{Unstable}}{}^{236}\mathrm{U} \to {}_{36}{}^{91}\mathrm{Kr}+{}_{56}{}^{142}\mathrm{Ba}+3{}_0{}^{1}n\mathit{+}energy \end{gathered}$$

As a result of the fission of uranium -$235$, the products aredata-custom-editor="chemistry" ${}_{36}{}^{91}\mathrm{Kr},{}_{56}{}^{142}\mathrm{Ba}$, neutrons, and energy.

 Neutrons react with additional $\mathrm{U}-235$ nuclei in these compounds, allowing nuclear chain reactions to occur.

Step 3: Explanation of option b

(b)  In a nuclear reactor, control rods are placed among uranium samples to slow down fission reactions.

     Because uranium fission produces multiple high-energy neutrons, the subsequent chain reaction is processed.

    Control rods absorb some of the uranium sample's fast-moving neutrons. Because fewer neutrons are accessible for chain reactions, we can better regulate fission and the quantity of energy produced.

    To slow down the fission reaction, control rods are placed among uranium samples in a nuclear reactor.