Chapter 15, Problem 15.45E

Naphthacene, ${\text{C}}_{\text{18}}{\text{H}}_{\text{12}}$, consists of four benzene rings in a row, each connected by sharing a $\text{C}-\text{C}$ bond. Naphthacene absorbs light at $\text{450}\text{.2}\text{nm}$. (a) If this corresponds to an electron going from $n=9$ to $n=10$ in a particle-in-a-box, what is the length of the naphthacene molecule? (b) If each benzene unit is $\text{0}\text{.280}\text{nm}$ wide, how good is this approximation?