Chapter 6, Problem 76QAP

The energy of any one-electron species in its nth state $\left(\text{n}=\text{principal}\text{quantum}\text{number}\right)$ is given by $\text{E}=-{\text{BZ}}^2/{\text{n}}^2$, where Z is the charge on the nucleus and B is $2.180\times {10}^{-18}\text{J}$. Find the ionization energy of the ${\text{Li}}^{2+}$ ion in its first excited state in kilojoules per mole.