Chapter 8, Problem 80RQ

A mixture of ${\text{H}}_{\text{2}}{\text{ and Cl}}_{\text{2}}$ is stable, but a bright flash of light passing through it can cause the mixture to explode. The light causes ${\text{Cl}}_{\text{2}}$ molecules to split into Cl atoms, which are highly reactive. What wavelength of light is necessary to cause the ${\text{Cl}}_{\text{2}}$ molecules to split? The bond energy of ${\text{Cl}}_{\text{2}}$ is 242.6 kJ per mole.