Calculate the concentration of SO2(ppm) that must be reached in polluted air (in ppm) if the dissolved gas is to produce a pH of 3.2 in raindrops without any oxidation of the gas.
Taking the mass of the atmosphere to be 6.0E15 metric tons, what mass of carbon must
be burned in order to increase the average carbon dioxide level in the atmosphere
by 110ppm by volume (in metric tons)?
a) Photosynthesis is estimated to produce 310.0 g (dry weight) of plant matter per square meter, 50% of which is carbon. Calculate the total number of grams of carbon "fixed" each year by 1000 square meters.
b) The photosynthetic reaction can be represented as:
6CO2 + 6H2O -> C6H12O6 + 6O2
Of the glucose produced, 50.0% is used by the plant to fuel respiration; the rest is converted to plant matter. Calculate the total moles of glucose produced annually in our reference 1000 square meter area.
c) Each mole of glucose produced represents the absorption of 2803 kJ of solar energy. If the average energy available from the sunlight over an eight-month period is 1.4 kJ/cm2 per day, what percentage of the incident solar energy is converted to chemical energy in our 1000 square meter area?
NOTE: Make sure to fill in the answers in the same order as the questions.
In 2000, the US accounted for one-fourth of the total world energy consumption
and both the US and world rates were growing at a 3.2 percent annual rate. Suppose the US
cut its growth rate to 0.3 percent, while the rest of the world growth propelled by the
needs of developing countries, continued to increase by the historic rate. What would be the
US share of total comsumption in 2050 (in percent)?
An analytical chemist determines that an estuarine water sample contains 1.5 g/L of sulfate ion. What is the
concentration in terms of (a) g/L of S (b) molar concentration of sulfate (c) normality (d) parts per million of sulfate
In manufacturing a fruit drink, citric acid is added to water in the amount of 0.1 mol/L. What is the pH of the resulting
solution?
(a) An acre of corn can produce about 300 gallons of ethanol, using only the kernel of the corn for conversion to ethanol. Assume the energy input to produce an acre of corn is 18000000 kJ. If a gallon of ethanol has an embodied energy in the ethanol of about 80000 kJ, calculate the ratio of embodied energy in the ethanol to the energy required to produce the corn.
(b) Assume the yield of corn stover (cobs, stalks, leaves) is 4.2 dry metric tons per acre. The extra energy required to convert the stover to ethanol is 15000 kJ/gallon; and one dry ton of stover can produce 80 gallons of ethanol. Assuming only 35 percent of the stover is removed for conversion to ethanol, what would be the new energy ratio calculated in (a) above?
How much Fe++ could be present in water containing 2 x 1e-02 M HCO3- (bicarbonate) without causing the precipitation of FeCO3 (Ksp=10**(-10.7))
Assume that due to dwindling supplies of crude oil and natural gas, the US embarks on a plan to implement the "hydrogen economy" for which hydrogen will be generated by electrolysis of water. The source of electricity is from photovoltaic (PV) conversion of sunlight in the southwestern US. (a) Assume that a flat plate PV system is used, with a solar conversion efficiency of 15 percent and a hydrogen production efficiency of 70 percent. Assume the average annual insolation in the southwest is 270 watts per square meter. Calculate the annual electrical energy produced in kJ/sq. meter. Calculate the weight of hydrogen (kg/sq. meter) produced per year.
(b) The US consumed 34 EJ of petroleum in 2000. How many square meters of PV collectors would be needed to supply the equivalent amount of energy in hydrogen?
The total mass of carbon contained in fossil fuels that was burned in the world from 1750 to 2000 was estimated to be 2.9 x E14 kg C. The amound of carbon released as carbon dioxide from agricultural expansion and deforestation over this period is estimated to be 1.2 x E14 kg C. The concentration of carbon dioxide in the atmosphere in 2000 was 360 ppm, corresponding to a total mass of 7.75E14 kg C. If the concentration of carbon dioxide in 1750 was 260 ppm, calculate the percentage of carbon dioxide from these two sources that remained in the atmosphere over the two and one-half century period.
(b) Plant studies indicate the net primary production (NPP) of organic carbon by photosynthesis may increase with increasing CO2 concentration in the atmosphere. Assume the increase of NPP in the biosphere is 0.34 of the percentage increase of atmospheric CO2. Given that the global NPP of the biosphere is currently estimated to be 1.1E14 kg C/yr, estimate how much more carbon (kg C) is being absorbed per year in the NPP compared to the amount that would be abosrbed if the atmospheric CO2 concentration was
was the same as in 1750.
(c) Anaerobic bacteria living at the bottom of a shallow inlet to a salt marsh are generating hydrogen sulfide as a by product of their metabolism. Although this compound is ordinarily found as a gas, it is reasonably soluble in water.
What is the maximum concentration of dissolved hydrogen sulfide species (H2S, HS-, and S2-)that could theoretically accumulate in the waters of the inlet if the pHis 6.0? (b) A small amount of dibromomethane has been spilled into the above inlet.
Assume the partial pressure of the H2S is 0.1 atm. If the principal process that will affect the fate of this species is its reaction with HS-, for which the relevant rate constant os 5.25E-5 /M/sec, how many days will be required for the dibromomethane concentration to decrease to 10% of its initial value?
The half-life of tritium is approximately 12 years. What will be the molar ratio of tritium to helium-3 in a sealed sampel after 25 years?
A stoppered flask at 25 C contains 250 mL water, 200 mL octanol, and 50 mL of air. An unknown mass of o-xylene is added to the
flask and allowed to partition among the phases. After equilibrium has been established, 5.0 mg of o-xylene are measured in the water.
What is the total mass (g) of o-xylene present in the flask?
The average pH of precipitation in rural areas is 6.50. Assuming that the pH
is controlled by the carbonate system, i.e., no anthropogenic acid gases are present
in the atmosphere, calculate the amount of calcium carbonate (mg) dissolved per liter
of rainwater. pKa1=6.33, KCO2=3.388e-02