Sub module 03, Homework page 1
#1 What would the concentration have been if the lake had a volume of 12,500 m^3? (Read all the choices)
a.) 40,000 ug/L
b.) 40 mg/L
c.) 4 x 10^4 ug/L
d.) Any of the above, b. is preferred.
#2 What would the rate constant be if the stream started to dry up and the flow rate became 50 m^3/hr?
a.) 0.010 hr
b.) 0.010 hr-1
c.) 0.010 / hr
d.) b.) or c.)
#3 What is the concentration in the lake 12.5 hours after the spill (assuming the stream does not dry up and the flow in and out remains 1000 m^3/hr) ?
a.) 82 mg/L
b.) 5 mg/L
c.)8.2 mg/L
d.) 500 mg/L
#4 Just by looking at the graph, how long does it take for the concentration to fall from 100 mg/L to 50 mg/L:
a.) 1 hr
b.) about 3 hr
c.) about 8 hr
d.) about 20 hr
#5 Using the spreadsheet, if you change the rate constant from 0.2 to 0.02, what is the concentration in the lake at 18 hours.
a.) 69.8 mg/L
b.) 16 mg/L
c.) 5 mg/L
d.) 98.6 mg/L
#6 What is the half-life in our lake system, to three decimal places, if the k = 0.2 / hr.
a.) 3.466 kg
b.) 3.466 min
c.) 3.466 hr
d.) None of the above.
#7 What is percentage of formaldehyde is in the water?
a.) 25%
b.) 50%
c.) 75%
d.) 99.8%
#8 What is percentage of dioxin is in the fish?
a.) 25%
b.) 50%
c.) 75%
d.) 97.8%