Question

Question: Natural lithium consists of 7.42 % ${}^{\mathbf{6}}\mathbf{Li}$ and 92.58 % ${}^{\mathbf{7}}\mathbf{Li}$. Much of tritium (${}_{\mathbf{1}}{}^{\mathbf{3}}\mathbf{H}$) used in experiments with fusion reactions is made by capture of neutrons by ${}^{\mathbf{6}}\mathbf{Li}$atoms.

1. Write a balanced nuclear equation for the process. What is the other particle produced?
2. After ${}^{\mathbf{6}}\mathbf{Li}$is removed from natural lithium, the remainder is sold for other uses. Is the molar mass of the leftover lithium greater or smaller than that of natural lithium?

Short answer

1. ${}_3{}^{6}Li+{}_0{}^{1}n\to {}_1{}^{3}He+{}_2{}^{4}He$
   
2. The average atomic mass of the leftover Lithium is greater than the natural Lithium.

Step-by-step solution

Balanced Nuclear reaction(a)

The ${}^6\mathrm{Li}$atom is bombarded with neutrons to get ${}^3\mathrm{H}$as one of the products. The balanced nuclear equation representing the fusion reaction is:

${}_3{}^6\mathrm{Li}+{}_0{}^1\mathrm{n}\to {}_1{}^3\mathrm{H}+{}_2{}^4\mathrm{He}$

The particle emitted along with the formation of tritium is an alpha particle.

 Step 2: Predicting the change in the molar mass of the leftover lithium(b)

${}^7\mathrm{Li}$is the naturally abundant isotope of Lithium. Since, the percentage of ${}^6\mathrm{Li}$ is very less as compared to ${}^7\mathrm{Li}$.

Therefore, the mass of the leftover lithium after depletion of ${}^6\mathrm{Li}$increases.