Chapter 6, Problem 12Q

(a)

Interpretation Introduction

Interpretation:

For the fission of U-235 induced by neutron, nuclear equation for the formation of bromine-87, lanthanum-146 and more neutrons has to be given.

Explanation of Solution

Given information,

Fission of U-235 induced by neutron, and gives bromine-87, lanthanum-146 and more neutrons.

Nuclear equation for the given process,

$\begin{array}{l}{}_{\text{0}}^{\text{1}}\text{n}\text{+}{}_{\text{92}}^{\text{235}}\text{U}\stackrel{}{\to }\left[{}_{\text{92}}^{\text{236}}\text{U}\right]\stackrel{}{\to }{}_{\text{57}}^{\text{146}}\text{La}\text{+}{}_{\text{35}}^{\text{87}}\text{Br+}{\text{3}}_{\text{0}}^{\text{1}}\text{n}\\ \text{Left}\text{side}\text{right}\text{side}\\ \text{sum}\text{of}\text{subscripts:}\text{0}\text{+92}\text{=}\text{92}\text{57}\text{+}\text{35}\text{+0}\text{=}\text{92}\\ \text{sum}\text{of}\text{superscripts:}\text{1}\text{+235}\text{=}\text{236}\text{146}\text{+}\text{87}\text{+3}\text{=}\text{236}\end{array}$

Uranium-236 is written in square brackets because it is an unstable intermediate in the above reaction.  Lifetime of this isotope is extremely small, so it will decompose immediately and will produce bromine-87, lanthanum-146 and neutrons.

(b)

Interpretation Introduction

Interpretation:

For the fission of U-235 induced by neutron, nuclear equation for the formation of a nucleus with 56 protons, a second with a total of 94 neutrons and protons and 2 additional neutrons has to be given.

Explanation of Solution

Given information,

Fission of U-235 induced by neutron, and gives a nucleus with 56 protons, a second with a total of 94 neutrons and protons and 2 additional neutrons.

Nuclear equation for the given process,

$\begin{array}{l}{}_{\text{0}}^{\text{1}}\text{n}\text{+}{}_{\text{92}}^{\text{235}}\text{U}\stackrel{}{\to }\left[{}_{\text{92}}^{\text{236}}\text{U}\right]\stackrel{}{\to }{}_{\text{56}}^{\text{140}}\text{Ba}\text{+}{}_{\text{36}}^{\text{94}}\text{Kr+}{\text{2}}_{\text{0}}^{\text{1}}\text{n}\\ \text{Left}\text{side}\text{right}\text{side}\\ \text{sum}\text{of}\text{subscripts:}\text{0}\text{+92}\text{=}\text{92}\text{56}\text{+}\text{36}\text{+0}\text{=}\text{92}\\ \text{sum}\text{of}\text{superscripts:}\text{1}\text{+235}\text{=}\text{236}\text{140}\text{+}\text{94}\text{+2}\text{=}\text{236}\end{array}$

Uranium-236 is written in square brackets because it is an unstable intermediate in the above reaction.  Lifetime of this isotope is extremely small, so it will decompose immediately and will produce Barium-140, Krypton-94 and two neutrons.