Chapter 31, Problem 2P

To determine

To identify: Whether the given reaction requires a threshold energy or not.

Explanation of Solution

Introduction:

Threshold energy is defined as the minimum energy required a molecule to take part in a reaction.

Consider the given reaction.

  ${}_1^2{\text{H}}^1{+}_1^2{\text{H}}^1{\stackrel{}{\to }}_2^3\text{He}+\text{n}$

Write the expression to calculate the energy for the reaction.

  $Q=2m_{\frac{2}{1}{\text{H}}^1}{c}^2-m_{\frac{3}{2}\text{He}}{c}^2$

Substitute the values of atomic mass in the above expression.

  $\begin{array}{c}Q=\left[2\left(2.014102u\right)-3.016029u-1.008665u\right]\left(931.5\frac{{\text{meV/c}}^2}{u}\right)\\ =3.270\text{meV}\end{array}$

Since, the value of $Q$ is positive. Hence, no threshold energy is required.

Conclusion:

Therefore, no threshold energy is required.