(a) When chlorine atoms react with atmospheric ozone, what are the products of the reaction?
Nitrogen oxides like NO2 and NO are a significant source of acid rain. For each of these molecules, write an equation that shows how an acid is formed from the reaction with water.

Key Concepts
Acid-Base Reactions
Formation of Nitric Acid
Formation of Nitrous Acid
(b) Based on average bond enthalpies, would you expect a photon capable of dissociating a C-Cl bond to have sufficient energy to dissociate a C-Br bond?
(b) If a limestone sculpture were treated to form a surface layer of calcium sulfate, would this help to slow down the effects of acid rain? Explain.
Alcohol-based fuels for automobiles lead to the production of formaldehyde (CH2O) in exhaust gases. Formaldehyde undergoes photodissociation, which contributes to photo- chemical smog: CH2O + hn ¡ CHO + H The maximum wavelength of light that can cause this reaction is 335 nm. (b) What is the maximum strength of a bond, in kJ/mol, that can be broken by absorption of a photon of 335-nm light?
Alcohol-based fuels for automobiles lead to the production of formaldehyde (CH2O) in exhaust gases. Formaldehyde undergoes photodissociation, which contributes to photo- chemical smog: CH2O + hn ¡ CHO + H The maximum wavelength of light that can cause this reac- tion is 335 nm. (d) Write out the formaldehyde photodis- sociation reaction, showing Lewis-dot structures.