The Federal Water Pollution Control Act (P.L. 92-500) specifies legally acceptab
ID: 819117 • Letter: T
Question
The Federal Water Pollution Control Act (P.L. 92-500) specifies legally acceptable methods for wastewater analysis. Analysis for cyanide is done according to the method outlined in
The Federal Water Pollution Control Act (P.L. 92-500) specifies legally acceptable methods for wastewater analysis. Analysis for cyanide is done according to the method outlined in "Standard Methods for the Examination of Waste Water." Mercuric chloride is used in the analytic procedure to decompose complex cyanides and 200mg are used per analysis. The Illinois Pollution Control Board has established Water Quality Standards that limit mercury (Hg only) to 0.0005ppm in any effluent. Permit holders are required to submit daily reports on their effluent. Will a permit holder discharging 100,000 gal/day be in violation of the cited standard if one cyanide analysis test is performed?Explanation / Answer
So the wording in this question is a little weird -- let me clarify what they're saying. These companies analyze cyanide levels by putting samples of Mercuric chloride in the water. The question is asking you if the mercury they're putting in the water through this test is too high a concentration. So you need to find out how mercuric chloride (HgCl2) dissolves in water, and if 200 mg in a 100,000 gallon sample is greater than 0.0005 ppm (in other words, a violation of the limit).
0.200 g HgCl2 / (271.52 g/mol HgCl2) = .0007366 mol HgCl2
0.0007366 mol HgCl2 = 0.0007366 mol Hg2+ (because one Hg2+ atom is made per HgCl2 molecule)
0.0007366 mol Hg2+ * (200.59 g/mol) = 0.1478 g = 147.8 mg Hg2+
100,000 gallons of H20 = 378541 kg
147.mg Hg2+ / 378541 kg H20 = 0.00039 mg/kg = 0.00039 ppm
This is less than .0005 ppm, so the company is NOT in violation.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.