environmental civil engineering 2

1. The biological degradation of the hazardous chemical TCE is a second order reaction in [TCE]. If the initial concentration is 200mg/L and it took 0.45 hr for the 45% to degrade. How long is needed to achieve

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a. 95% degradation

b. 99% degradation

c. A second order reaction occurring in a plug flow reactor at 25 degree Celsius is known to have a half life 0.75hr. If the initial concentration is 200mg/L: How long is required to achieve 90% completion?

d. What is the detection time if the flow rate is 10 gallons per minute?

e. How long is required to achieve 99% completion at 35% degree Celsius if Ó¨ =1.2?

2. (20 pts).

A. What is the pH of the solution of 2,4 dinitrophenol, a week acid which is 35%, dissociated. KA for 2,4 dinitrophenol is 10-7.85

B. calculate the concentration of the following in μg/L? (Ca = 40.08; Na = 23; K = 39; S =32; Cl -35.5; H =1)

i. 0.055N Ca(CH)2

ii. 0.044M KCI

iii. 0.084 N Na2SO4

3. (20 pts)

A. Formaldehyde is commonly found in the indoor air of improperly designed and the constructed buildings. If the concentration of formaldehyde in a home is 1.0 ppmv and the inside of the room is 1000m3, what mass (grams) of formaldehyde vapor is inside the home? Assume T=30 degree Celsius and P = 1tam. The molecular weight of formaldehyde is 30. R =80205 x 10-5 atm, =.m3/mole. K.

B. A 3.5 million gallon water reservoir in Avila Beach in California was contaminated by oxygenated gasoline containing 0.5% by weight of MBTE when the pipeline busted. If the estimated volume of gasoline released into the reservoir was 10000 gallons and the specific gravity of gasoline is 0.880 calculate in ppb the concentrations of

i. Gasoline in the reservoir

ii. MBTE in the reservoir

A. Total Hardness:

Total hardness as CaCo3

B. Alkalinity < Total Hardness



which mean:

C. Alkalinity due to HCO3