Ozone (O₃) has an absorptivity at 300. nm of 0.000500 torr⁻¹ cm⁻¹. In atmospheric chemistry the amount of ozone in the atmosphere is quantified using the Dobson unit (DU), where 1 DU is equivalent to a 10⁻² mm thick layer of ozone at 1 atm and 273.15 K.

a. Calculate the absorbance of the ozone layer at 300. nm for a typical coverage of 300. DU

b. Seasonal stratospheric ozone depletion results a decrease in ozone coverage to values as low as 120. DU. Calculate the absorbance of the ozone layer at this reduced coverage.

In each part, also calculate the transmission from the absorbance using Beer’s law.