Problem 1
Which of the following atmospheric gases is present in highest concentration in dry air? (a) \(\mathrm{N}_{2} \mathrm{O}\) (b) \(\mathrm{CH}_{4}\) (c) \(O_{3}\) (d) \(\mathrm{CO}\)
Problem 2
Many chemical reactions that occur in the atmosphere and stratosphere involve free radicals. Free radical formation occurs when a photon of light is absorbed and the energy of the radiation being absorbed causes a chemical bond in the compound to break. Which of the following bonds requires the most energy (and the most energetic radiation) to be broken? (a) The oxygen-oxygen bond in \(\mathrm{O}_{2}\) (b) The chlorine-carbon bond in \(\mathrm{CCl}_{2} \mathrm{F}_{2}\) (c) The oxygen-oxygen bond in \(\mathrm{O}_{3}\)
Problem 4
Assume the average \(\mathrm{CO}_{2}\) concentration in the atmosphere is 406 ppm (as of January 2017 ). The actual concentration of \(\mathrm{CO}_{2}\) at different sites will vary. Speculate on whether the concentration of \(\mathrm{CO}_{2}\) would be expected to be higher, lower, or the same as this average value in a typical large city.
Problem 6
Suppose you find the CO concentration in your home is \(10 .\) ppm by volume at 1.00 atm pressure and \(25^{\circ} \mathrm{C} .\) What is the CO concentration in \(\mathrm{mg} / \mathrm{L}\) and in ppm by mass. (The average molar mass for dry air is \(28.96 \mathrm{g} / \mathrm{mol}\) at 1.00 atm pressure and \(\left.25^{\circ} \mathrm{C} .\right)\)
Problem 7
Various reagents are added to water supplies to kill pathogens and make the water safe to drink. Among the substances listed below, which does not serve that function? (a) \(\mathrm{Cl}_{2}\) (b) \(\mathrm{O}_{3}\) (c) \(\mathrm{Ca}(\mathrm{ClO})_{2}\) (d) \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\)
Problem 8
Which of the following statements is not correct? (a) Phosphates enhance the growth of algae in surface water. (b) Melting of the polar ice cap will result in a rise in sea levels. (c) Heavy metal toxicity can result from the presence of metal compounds of lead, cadmium, and mercury in water supplies. (d) Reverse osmosis is a good way to effect desalination.
Problem 13
Although there are a number of magnesiumcontaining minerals, the commercial source of this metal is seawater. Treatment of seawater with \(\mathrm{Ca}(\mathrm{OH})_{2}\) gives insoluble \(\mathrm{Mg}(\mathrm{OH})_{2} .\) This reacts with HCl to produce \(\mathrm{MgCl}_{2}\), which is dried, and the metal is obtained by electrolysis of the molten salt. Write balanced net ionic equations for the three reactions described here.
Problem 15
A 2010 article in Science magazine described "Sewage Treatment with Anammox." IB. Kartal, I. G. Kuenen, and M. C. M. van Loosdrecht, Science, Vol. \(328,\) pp. \(702-703,2010 .\) The authors noted that "Fixed nitrogen such as ammonium and nitrate [ions] must be removed [from sewage] to avoid toxic algal blooms in the environment." One approach to removing ammonium ions is to use ammonium-oxidizing (anammox) bacteria. Two (unbalanced) reactions that are involved are: $$\begin{array}{l}\mathrm{NH}_{4}^{+}(\mathrm{aq})+\mathrm{NO}_{2}^{-}(\mathrm{aq}) \rightarrow \mathrm{N}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell) \\\\\mathrm{NH}_{4}^{+}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{NO}_{2}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)\end{array}$$ Balance these two equations in acid solution.
Problem 17
Which of the following is a renewable energy resource? (a) nuclear fusion (b) hydroelectric power (c) natural gas (d) coal
Problem 18
In the United States (and worldwide), fossil fuels provide the larger source of energy. What is the second largest energy source? (a) hydroelectric (b) solar (c) nuclear (d) geothermal
