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문제 32a
An important reaction in the formation of photochemical smog is the photodissociation of NO : NO2 + hv → NO(g) + O(g) The maximum wavelength of light that can cause this reac- tion is 420 nm. (a) In what part of the electromagnetic spec- trum is light with this wavelength found?
- The atmosphere of Mars is 96% CO2, with a pressure of approximately 6 * 10⁻³ atm at the surface. Based on measurements taken over a period of several years by the Rover Environmental Monitoring Station (REMS), the average daytime temperature at the REMS location on Mars is –5.7 °C (22 °F), while the average nighttime temperature is –79 °C (–109 °F). This daily variation in temperature is much larger than what we experience on Earth. What factor plays the largest role in this wide temperature variation, the composition or the density of the atmosphere?
문제 34
문제 35
What is the molarity of Na+ in a solution of NaCl whose salinity is 5.6 if the solution has a density of 1.03 g>mL?
문제 36
Phosphorus is present in seawater to the extent of 0.07 ppm by mass. Assuming that the phosphorus is present as dihydrogenphosphate, H2PO4-, calculate the correspond-ing molar concentration of H2PO4- in seawater.
문제 37a
The enthalpy of evaporation of water is 40.67 kJ/mol. Sunlight striking Earth's surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). (a) Assuming that evaporation of water is due only to energy input from the Sun, calculate how many grams of water could be evaporated from a 1.00 square meter patch of ocean over a 12-h day
문제 38b
The enthalpy of fusion of water is 6.01 kJ/mol. Sunlight striking Earth's surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). (b) The specific heat capacity of ice is 2.032 J/g°C. If the initial temperature of a 1.00 square emter patch of ice is -5.0°C, what is its final temperature after being in sunlight for 12 h, assuming no phase changes and assuming that sunlight penetration uniformly to a depth of 1.00 cm?
- At the first-stage recovery of magnesium from seawater, the precipitation of Mg(OH)2 with CaO occurs in the following reaction: Mg2+(aq) + CaO(s) + H2O(l) → Mg(OH)2(s) + Ca2+(aq). What mass of CaO, in grams, is needed to precipitate 1000 lb of Mg(OH)2?
문제 39
- Gold is found in seawater at very low levels, about 0.05 ppb by mass. Assuming that gold is worth about $1300 per troy ounce, how many liters of seawater would you have to process to obtain $1,000,000 worth of gold? Assume the density of water is 1.03 g/mL and that your gold recovery process is 50% efficient.
문제 40
문제 42
The Ogallala aquifer described in the Closer Look box in Section 18.3, provides 82% of the drinking water for the people who live in the region, although more than 75% of the water that is pumped from it is for irrigation. Irrigation withdrawals are approximately 18 billion gallons per day. (a) Assuming that 2% of the rainfall that falls on an area of 600,000 km2 recharges the aquifer, what average annual rainfall would be required to replace the water removed for irrigation?
- List the common products formed when an organic material containing the elements carbon, hydrogen, oxygen, sulfur, and nitrogen decomposes (a) under aerobic conditions, (b) under anaerobic conditions.
문제 43
문제 45
The organic anion
is found in most detergents. Assume that the anion under-goes aerobic decomposition in the following manner: C18H29SO3- + 51 O2 → 36 CO2(aq) + 28 H2O (l) + 2 H+(aq) + 2 SO42-(aq) What is the total mass of O2 required to biodegrade 10.0 g of this substance?
문제 47
Magnesium ions are removed in water treatment by the addition of slaked lime, Ca(OH)2. Write a balanced chemical equation to describe what occurs in this process
문제 48
In the lime soda process once used in large scale munici-pal water softening, calcium hydroxide prepared from lime and sodium carbonate are added to precipitate Ca2+ as CaCO3(s) and Mg2+ as Mg(OH)2(s): Ca2+(aq) + CO32-(aq) → CaCO3(s) Mg2+(aq) + 2 OH-(aq) → MgOH2(aq) How many moles of Ca(OH)2 and Na2CO3 should be added to soften (remove the Ca2+ and Mg2+) 1200 L of water in which [Ca2+] = 5.0x10-4 M and [Mg2+] = 7.0x10-4 M?
문제 49
(a) What are trihalomethanes (THMs)? (b) Draw the Lewis structures of two example THMs.
- Suppose that tests of a municipal water system reveal the presence of bromate ion, BrO3-. What are the likely origins of this ion?
문제 50
- One of the principles of green chemistry is that it is better to use as few steps as possible in making new chemicals. In what ways does following this rule advance the goals of green chemistry? How does this principle relate to energy efficiency?
문제 51
- Discuss how catalysts can make processes more energy efficient.
문제 52
문제 53a
A reaction for converting ketones to lactones, called the Baeyer–Villiger reaction,
is used in the manufacture of plastics and pharmaceu- ticals. 3-Chloroperbenzoic acid is shock-sensitive, how- ever, and prone to explode. Also, 3-chlorobenzoic acid is a waste product. An alternative process being developed uses hydrogen peroxide and a catalyst consisting of tin deposited within a solid support. The catalyst is readily recovered from the reaction mixture. (a) What would you expect to be the other product of oxidation of the ketone to lactone by hydrogen peroxide?
문제 56
In the following three instances, which choice is greener in a chemical process? Explain. (a) A reaction that can be run at 350 K for 12 h without a catalyst or one that can be run at 300 K for 1 h with a reusable catalyst.
문제 59
Show how Equations 18.7 and 18.9, and the combination reaction that leads to the formation of molecular oxygen, 2O(𝑔)⟶O2(𝑔), can be added to give Equation 18.10.
- Halons are fluorocarbons that contain bromine, such as CBrF3. They are used extensively as foaming agents for fighting fires. Like CFCs, halons are very unreactive and ultimately can diffuse into the stratosphere. (b) Propose a mechanism by which the presence of halons in the stratosphere could lead to the depletion of stratospheric ozone.
문제 61
문제 62
(a) What is the difference between a CFC and an HFC?
문제 64b
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.
문제 66a
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?
문제 67
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?
문제 68
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.)
문제 69a,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.
문제 69d
Write balanced chemical equations for each of the following reactions: (d) Nitrogen dioxide dissolves in water to form nitric acid and nitric oxide.
문제 70b
(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+?
문제 71a
(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?