Chapter 7, Problem 7.100QP

Ozone in the stratosphere absorbs ultraviolet light of wavelengths shorter than 320 nm, thus filtering out the most energetic radiation from sunlight. During this absorption, an ozone molecule absorbs a photon, which breaks an oxygen-oxygen bond, yielding an oxygen molecule and an oxygen atom:

${\text{O}}_3(g)+hv\to {\text{O}}_2(g)+\text{O}(g)$

(Here, hv denotes a photon.) Suppose a flask of ozone is irradiated with a pulse of UV light of wavelength 275 nm. Assuming that each photon of this pulse that is absorbed breaks up one ozone molecule, calculate the energy absorbed per mole of O₂ produced, giving the answer in kJ/mol.