Threshold / NOEL Levels of Chemical Toxins
The threshold/NOEL level found for a particular chemical from animal studies is 0.006 mg/kg body weight per day. The only source for the chemical is freshwater fish, where it occurs at an average level of 0.2 ppm. What is the maximum average daily consumption(g) of such fish that would keep exposure level below the ADI or RfD fo ...continues
How many metric tons of 5%-S coal would be needed to yield the H2SO4 required to produce a 1.5cm rainfall of pH 2.00 over an area of 100 square kilometers?
How do you work out alkalinity from: [H^+] 2.3×10-5 [Ca^2+] 23.2 mg/L [CO3^2- ] 17.4 mg/L [HCO3^-] 5.7 mg/L
Threshold / NOEL Levels of Chemical Toxins in Fishes
The threshold/NOEL level found for a particular chemical from animal studies is 0.005 mg/kg body weight per day. The only source for the chemical is freshwater fish, where it occurs at an average level of 0.2 ppm. What is the maximum average daily consumption(g) of such fish that would keep exposure level below the ADI or RfD fo ...continues
Comparing the Amount of Coal and Uranium Required to Produce Electricity
When some large nuclear plants run at full capacity, they produce about 1900 MW of electrical power. At this rate, what mass of 235U (kg) would it consume per year if the efficiency of converting nuclear energy to electricity is 33%? How many metric tons of coal would be required to supply the same amount of electricity? Hint ...continues
Reaction Kinetics : Concentration at Equilibrium
What is the fraction of NTA present after HT2- has been brought to equilibrium with solid PbCO3 at pH 7.00, in a medium in which [HCO3-] = 1.50E-3 M?
Poly-Brominated Diphenyl Ethers ( PBDEs ) as Congeners and their Potential Toxicity
Please answer and explain where appropriate The brominated flame retardants consist of 209 congeners with different physical-chemical properties and therefore behave differently in the environment. Congener/ Water Solublity (mol/L)/Log KOA/Log KOW/Human BMF 4, 4'-dibromo / 6.57 x 10-7 / 8.64 / 5.86 / - 2,2',4,4'-tetrabro ...continues
How many metric tons of 5% S coal would be needed to yield the H2SO4 required to produce a 3.00 cm rainfall of pH 2.00 over a 100 km2 area?
Nitrogen Content and Biochemical Oxygen Demand ( BOD )
We have a wastewater source whose flow is 2000 m3 per day; the stated BOD or bio-chemical oxygen demand in that wastewater is given as 5000 mg/l. We are to use urea (NH2)2CO to provide nitrogen to the wastewater in a specific ratio of 100 parts (BOD) to 5 parts(Nitrogen) --- no more or no less. The mass fraction of N in ur ...continues
Calcite in Seawater : pH, Calcium Ion and Carbonate Concentration
Please see the attached file for the fully formatted problems. KH = 3.3 x 10-7 Ka1 = 4.5 x 10-7 (carbonic acid) Ka2 = 4.7 x 10-11 (bicarbonate) Ksp = 5 x 10-9 (calcite) Assuming equilibrium between the atmosphere, seawater, and calcite: [H+]3 = KH2Ka12Ka2PCO22 2Ksp [HCO3-] = 2Ksp{H+]2 ...continues
