Hydrogen question

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 10 percent and a hydrogen production efficiency of 60 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 consum... click for more

Environmental chemistry - change in carbon

The total mass of Carbon contained in fossil-fuels that were burned in the world from the year 1750 to the year 2000 was estimated to be 2.7 x E14 kg C. The amound of carbon released as CO2 from agricultural expansion and deforestation over this period is estimated to be 1.3 x E14 kg C. The concentration of CO2 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 250 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 ma... click for more

Environmental chemistry question - short

Assume that waste will contain 295.0 mg/L of biodegradable CH2O and will be processed through a 200000.0 L/day sewage treatment plant which converts 40% of the waste to CO2 and H2O. Calculate the volume (in Liters) of air (at 25 degrees C, 1 atm) required for this conversion. Assume that the O2 is transferred to the water with 20% efficiency. Hint: Calculate mass of carbohydrate processed, use chemical equations to calculate mol oxygen needed to oxidize the carbohydrate, and the volume of air needed.

Calculation of calcium carbonate dissolved per liter.

The average pH of precipitation in rural areas is 5.80. 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 Hint: pCO2=3.162e-04

carbonate eq problem

How much Fe++ (in moles per litre) could be present in water which contains 1.4 x 1e-02 M HCO3- (bicarbonate) without causing the precipitation of FeCO3 (Ksp=10^(-10.7)) Hint: carbonate eq.