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- Explain, using Le Châtelier’s principle, why the equilibrium constant for the formation of NO from N2 and O2 increases with increasing temperature, whereas the equilibrium constant for the formation of NO2 from NO and O2 decreases with increasing temperature.
Problem 68
Problem 69a
Natural gas consists primarily of methane, CH4(g). (a) Write balanced chemical equation for the complete combustion of methane to produce CO2(g) as the only carbon-containing product.
Problem 69b
Natural gas consists primarily of methane, CH4(g). (b) Write a balanced chemical equation for the incomplete combustion of methane to product CO(g) as the only carbon-containg product.
Problem 71a
One of the possible consequences of climate change is an increase in the temperature of ocean water. The oceans serve as a 'sink' for CO2 by dissolving large amounts of it.
(a) The figure below shows the solubility of CO2 in water as a function of temperature. Does CO2 behave more or less similarly to other gases in this respect?
Problem 72
The rate of solar energy striking Earth averages 168 watts per square meter. The rate of energy radiated from Earth's surface averages 390 watts per square meter. Comparing these numbers, one might expect that the planet would cool quickly, yet it does not. Why not?
Problem 73
The solar power striking Earth every day averages 168 watts per square meter. The highest ever recorded electrical power usage in New York City was 13,200 MW. A record established in July of 2013. Considering that present technology for solar energy conversion is about 10% efficient, from how many square meters of land must sunlight be collected in order to provide this peak power? (For compar- ison, the total area of New York City is 830 km2.)
Problem 74a,b,c
Write balanced chemical equations for each of the following reactions: (a) The nitric oxide molecule undergoes photodissociation in the upper atmosphere. (b) The nitric oxide molecule undergoes photoionization in the upper atmosphere. (c) Nitric oxide undergoes oxidation by ozone in the stratosphere.
Problem 74d
Write balanced chemical equations for each of the following reactions: (d) Nitrogen dioxide dissolves in water to form nitric acid and nitric oxide.
- Explain why Mg(OH)2 precipitates when CO32- ion is added to a solution containing Mg2+.
Problem 75
Problem 75b
(b) Will Mg(OH)2 precipitate when 4.0 g of Na2CO3 is added to 1.00 L of a solution containing 125 ppm of Mg2+?
Problem 76a
(a) The EPA threshold for acceptable levels of lead ions in water is 615 ppb. What is the molarity of an aqueous solution with a concentration of 15 ppb?
Problem 76b
(b) Concentrations of lead in the bloodstream are often quoted in units of μg/dL. Averaged over the entire country, the mean concentration of lead in the blood was measured to be 1.6 μg/dL in 2008. Express this concentration in ppb.
- As of the writing of this text, EPA standards limit atmospheric ozone levels in urban environments to 84 ppb. How many moles of ozone would there be in the air above Los Angeles County (area about 4000 square miles; consider a height of 100 m above the ground) if ozone was at this concentration?
Problem 77
Problem 78a
The estimated average concentration of NO2 in air in the United States in 2006 was 0.016 ppm. (a) Calculate the partial pressure of the NO2 in a sample of this air when the atmospheric pressure is 755 torr (99.1 kPa).
Problem 79a
In 1986 an electrical power plant in Taylorsville, Georgia, burned 8,376,726 tons of coal, a national record at that time. (a) Assuming that the coal was 83% carbon and 2.5% sulfur and that combustion was complete, calculate the number of tons of carbon dioxide and sulfur dioxide produced by the plant during the year.
Problem 79b
In 1986 an electrical power plant in Taylorsville, Georgia, burned 8,376,726 tons of coal, a national record at that time. (b) If 55% of the SO2 could be removed by reaction with powdered CaO to form CaSO3, how many tons of CaSO3 would be produced?
Problem 80
The water supply for a midwestern city contains the following impurities: coarse sand, finely divided particulates, nitrate ions, trihalomethanes, dissolved phosphorus in the form of phosphates, potentially harmful bacterial strains, dissolved organic substances. Which of the following processes or agents, if any, is effective in removing each of these impurities: coarse sand filtration, activated carbon filtration, aeration, ozonization, precipitation with aluminum hydroxide?
Problem 82b
The concentration of H2O in the stratosphere is about 5 ppm. It undergoes photodissociation according to: H2O(g) → H(g) + OH(g) (b) Using Table 8.3, calculate the wavelength required to cause this dissociation.
Problem 82c
The concentration of H2O in the stratosphere is about 5 ppm. It undergoes photodissociation according to: H2O(g) → H(g) + OH(g)
(c) The hydroxyl radical, OH, can react with ozone, giving the following reactions:
OH(g) + O3(g) → HO2(g) + O2(g)
HO2(g) + O(g) → OH(g) + O2(g)
What overall reaction results from these two elementary reactions? What is the catalyst in the overall reaction? Explain.
- Bioremediation is the process by which bacteria repair their environment in response, for example, to an oil spill. The efficiency of bacteria for 'eating' hydrocarbons depends on the amount of oxygen in the system, pH, temperature, and many other factors. In a certain oil spill, hydrocarbons from the oil disappeared with a first-order rate constant of 2 * 10 s. At that rate, how many days would it take for the hydrocarbons to decrease to 10% of their initial value?
Problem 83
- A reaction that contributes to the depletion of ozone in the stratosphere is the direct reaction of oxygen atoms with ozone: O(g) + O3(g) → 2 O2(g). At 298 K, the rate constant for this reaction is 4.8 × 10⁵ M⁻¹ s⁻¹. Would you expect this reaction to occur via a single elementary process? Explain why or why not.
Problem 86
Problem 87b
The following data were collected for the desturction of O3 by H (O3 + H → O2 + OH) at very low concentrations (b) Calculate the rate constant
- The degradation of CF3CH2F (an HFC) by OH radicals in the troposphere is first order in each reactant and has a rate constant of k = 1.6x10^8 M-1s-1 at 4 °C. If the tropospheric concentrations of OH and CF3CH2F are 8.1x10^5 and 6.3x10^8 molecules/cm3, respectively, what is the reaction rate at this temperature in M/s?
Problem 88
Problem 89
The Henry's law constant for CO2 in water at 25 °C is 3.1x10^-2 M atm-1. (a) What is the soubility of CO2 in water at this temperature if the soltuion is in contact with air at normal atmospheric pressure?
Problem 90a
The precipitation of Al(OH)3 (Ksp) = 1.3⨉10-33) is sometimes used ot purify water. (a) Estimate the pH at which precipitation of Al(OH)3 will begin if 5.0 lb of Al2(SO4)3 is added to 2000 gal of water
Problem 91c
The valuable polymer polyurethane is made by a condensa- tion reaction of alcohols (ROH) with compounds that con- tain an isocyanate group (RNCO). Two reactions that can generate a urethane monomer are shown here: (i)
(ii)
(c) If you wanted to promote the formation of the isocyanate intermediate in each reaction, what could you do, using Le Châtelier's principle?
Problem 92
The pH of a particular raindrop is 5.6.
(a) Assuming the major species in the raindrop are H2CO3(aq), HCO3-(aq) and CO32- (aq), Calculate the concentrations of these species in the raindrop, assuming the total carbonate concentration is 1.0 * 10-5 M. The appropriate Ka values are given in Table 16.3.
(b) What experiments could you do to test the hypothesis that the rain also contains sulfur-containing species that contribute to its pH? Assume you have a large sample of rain to test.
Problem 92b
The pH of a particular raindrop is 5.6. (b) What experiments could you do to test the hypothesis that the rain also contains sulfur-containing species that contribute to its pH? Assume you have a large sample of rain to test.