60. A 155 mL sample of rainwater is titrated using 0.0095 M NaOH solution. If 4.8 mL of the NaOH solution was required to reach the endpoint, what was the pH of the rainwater? The computer gave the following hint: Calculate the number of moles of NaOH to reach the endpoint. From this calculate the hydrogen ion concentration and ...continues
Combustion temps; Calc. Concentration of nitric oxide in equilibrium with....
124. At combustion temperatures, the equilibrium constant for the reaction N2 + O2 -> 2NO is about 5.0E-14. Calculate the concentration of nitric oxide that is in equilibrium with atmospheric levels of nitrogen and oxygen.
Calculate temps; solar irradiance is 1500 W/m2 and total planetary albedo... AAHHH!
127. Calculate the temperature (K) of the earth if there were no greenhouse effect. Assume the solar irradiance is 1500 W/m2 and the total planetary albedo is 25 percent. (The Stefan Boltzmann constant is 0.567e-07 W/m2/K4). ****I've tried to answer this twice, but both times I was incorrect and the program gave the following h ...continues
What mass of Calcium carbonate is required to react with the sulfur produced...
136. What mass of calcium carbonate is required to react with the sulfur that is produced by burning 1000 kg of coal that contains 3.6 % sulfur by mass? ***I gave this one a shot but I was wrong. The program offered the following hint (that I thought I did!!): Using a chemical equation convert the mass of coal to a mass of sulfu ...continues
Conc. of HCB due to bioconcentration in the fat of fish...waters containing .000010 ppm...
180. For HCB, log Kow = 8.0. What would be the predicted concentration of HCB due to bioconcentration in the fat of fish that swim in waters containing 0.000010 ppm of the chemical? ***I answered this incorrectly and the program offered the following hint: Remember definition of octanol-water partition coefficient.
90. What is the redox potential of an acid mine water sample having Fe3+ = 7 x E-03 M and Fe2+ = 5 x E-04 M given that E0 for the Fe3+/Fe2+ couple is 0.77v.
How much Fe++ could be present in water containing 2 x 1e-02 M HCO3- .....
146. 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))? ***I don't even know where to start.
Steady state conc. of O2 radicals is 0.04 ppmv @ 25 deg C
Please note: this is the second time that this question has been posted. The answer is NOT a. 4.00 x 10 ^-8 atm, b. 1.63 x 10^-9 mol/L, c. =9.86 x 10 ^13 molecules/cm^3 121. During a photochemical smog episode in the coastal city of Seattle, the steady-state concentration of oxygen radicals at ground level was measured to b ...continues
Combustion temps; Calc. Concentration of nitric oxide in equilibrium with....
NOTE: This is the second time that this question has been posted, so please DO NOT respond unless you are 100% sure about your response. The answer is NOT 3.87 x 10^-9 M. 124. At combustion temperatures, the equilibrium constant for the reaction N2 + O2 -> 2NO is about 5.0E-14. Calculate the concentration of nitric oxide that ...continues
186) A 10.0 mL sample of river water was titrated with 0.0010 M Na2Cr2O7 and required 8.3 mL to reach the end-point. What is the chemical oxygen demand, in milligrams of O2 per liter, of the sample?
