Problem 30
Nobel laureate W. Sherwood Rowland referred to the ozone layer as the Achilles heel of our atmosphere. Explain the metaphor.
Problem 31
In the abstract of a talk he gave in 2007 , Nobel laureate W. Sherwood Rowland wrote "Solar UV radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation." a. What is the most energetic fraction? b. How does solar UV radiation "create an ozone layer"?
Problem 37
The average length of an \(\mathrm{O}-\mathrm{O}\) single bond is \(132 \mathrm{pm}\). The average length of an \(\mathrm{O}-\mathrm{O}\) double bond is \(121 \mathrm{pm}\). What do you predict the \(\mathrm{O}-\mathrm{O}\) bond lengths will be in ozone? Will they all be the same? Explain your predictions.
Problem 38
Consider the Lewis structures for \(\mathrm{SO}_{2}\). How do they compare with the Lewis structures for ozone?
Problem 39
Even if you have skin with little pigment, you cannot get a tan from standing in front of a radio. Why?
Problem 46
The free radical \(\mathrm{CF}_{3} \mathrm{O} \cdot\) is produced during the decomposition of HFC-134a. a. Propose a Lewis structure for this free radical. b. Offer a possible reason why \(\mathrm{CF}_{3} \mathrm{O} \cdot\) does not cause ozone depletion.
Problem 48
Polar stratospheric clouds (PSCs) play an important role in stratospheric ozone depletion. a. Why do PSCs form more often over Antarctica than in the Arctic? b. Reactions occur more quickly on the surface of PSCs than in the atmosphere. One such reaction is the reaction of hydrogen chloride and chlorine nitrate \(\left(\mathrm{ClONO}_{2}\right)\), two species that do not deplete ozone, to produce a chlorine molecule and nitric acid \(\left(\mathrm{HNO}_{3}\right)\). Write the chemical equation. c. The chlorine molecule produced does not deplete ozone either. However, when the Sun returns to the Antarctic in the springtime, it is converted to a species that does. Show how with a chemical equation.
Problem 51
Resonance structures can be used to explain the bonding in charged groups of atoms as well as in neutral molecules, such as ozone. The nitrate ion, \(\mathrm{NO}_{3}{ }^{-}\), has one additional electron plus the outer electrons contributed by nitrogen and oxygen atoms. That extra electron gives the ion its charge. Draw the resonance structures, verifying that each obeys the octet rule.
Problem 52
Although oxygen exists as \(\mathrm{O}_{2}\) and \(\mathrm{O}_{3}\), nitrogen exists only as \(\mathrm{N}_{2}\). Propose an explanation for these facts.
Problem 53
The chemical formulas for a CFC, such as CFC-11 \(\left(\mathrm{CCl}_{3} \mathrm{~F}\right)\), can be figured out from its code number by adding 90 to it to get a three-digit number. For example, with \(\mathrm{CFC}-11\) you get \(90+11=101\). The first digit is the # of \(\mathrm{C}\) atoms, the second is the # of \(\mathrm{H}\) atoms, and the third is the # of \(\mathrm{F}\) atoms. Accordingly, \(\mathrm{CCl}_{3} \mathrm{~F}\) has \(1 \mathrm{C}\) atom, no \(\mathrm{H}\) atoms, and \(1 \mathrm{~F}\) atom. All remaining bonds are assumed to be chlorine. a. What is the chemical formula for CFC-12? b. What is the code number for \(\mathrm{CCl}_{4}\) ? c. Does this "90" method work for HCFCs? Use \(\mathrm{HCFC}-22\left(\mathrm{CHClF}_{2}\right)\) in explaining your answer. d. Does this method work for halons? Use Halon-1301 \(\left(\mathrm{CF}_{3} \mathrm{Br}\right)\) in explaining your answer.
