Chapter 21

Water and sulfur dioxide are both polar molecules, and their geometry is similar. Why is ${\mathrm{SO}}_2$ not considered a major greenhouse gas?

What is photochemical smog? List the factors that favor the formation of photochemical smog.

What are primary and secondary pollutants?

Identify the gas that is responsible for the brown color of photochemical smog.

The safety limits of ozone and carbon monoxide are 120 ppb by volume and 9 ppm by volume, respectively. Why does ozone have a lower limit?

Suggest ways to minimize the formation of photochemical smog.

In which region of the atmosphere is ozone beneficial? In which region is it detrimental?

The gas-phase decomposition of peroxyacetyl nitrate (PAN) obeys first-order kinetics: $${\mathrm{CH}}_3{\mathrm{COOONO}}_2⟶{\mathrm{CH}}_3\mathrm{COOO}+{\mathrm{NO}}_2$$ with a rate constant of $4.9\times {10}^{-4}{\mathrm{s}}^{-1}.$ Calculate the rate of decomposition (in $M/\mathrm{s}$ ) if the concentration of PAN is 0.55 ppm by volume. Assume STP conditions.

On a smoggy day in a certain city, the ozone concentration was 0.42 ppm by volume. Calculate the partial pressure of ozone (in atm) and the number of ozone molecules per liter of air if the temperature and pressure were ${20.0}^{\circ }\mathrm{C}$ and $748\mathrm{mmHg}$, respectively.

List the major indoor pollutants and their sources.