TEST-2B Key

TEST-2B Key - YELLOW Introduction to Environmental...

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YELLOW Introduction to Environmental Engineering (CE 3501) EXAM 2 4/1/10 Name PART A: SHORT ANSWER, 4 points each 1. What produces acid rain? a. H 2 O + SOx b. H 2 O + ozone c. H 2 O + NOx d. a and c e. all of the above You have a water that contains the following: 85 mmol/L Ca 2+ 26 mmol/L Mg 2+ 132 mmol/L Na + 25 mmol/L K + 19 mmol/L SO 4 2- 145 mmol/L Cl - 196 mmol/L HCO 3 - 2. What is its alkalinity? a. 628 mmol/L b. 379 mmol/L c. 360 mmol/L d. 196 mmol/L e. 215 mmol/L ?±??±????² = °³´ 3 + 2 ³´ 3 2 + ´° − ° + Assuming a neutral pH the carbonate, hydroxide and hydrogen concentrations will be negligible. Thus: alkalinity = barcarbonate concentration=196. 3. What is the total hardness of the water? a. 268 mmol/L b. 111 mmol/L c. 130 mmol/L d. 379 mmol/L e. 628 mmol/L µ° = ³? 2+ + ¶· 2+ = 85 + 26 = 111
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4. What is the non-carbonate hardness of water (in very general terms)? a. the smaller of the alkalinity or the total hardness b. the same as the total hardness c. the larger of the alkalinity or the total hardness d. the sum of the multivalent cations e. the difference between the total hardness and the carbonate hardness You walk into a lab and find an aerated water sample (t=0). The sample is labeled and shows that it was collected exactly 4 days earlier (t=-4). You begin a BOD test on the water sample by diluting 25 mL of the sample (total volume 300 mL, DO i = 9 mg/L (t=0)). Five days later (t=5) the DO is 1.8 mg/L. 5. What is the BOD
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This note was uploaded on 11/10/2011 for the course CE 3502 taught by Professor Hill during the Spring '08 term at Minnesota.

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TEST-2B Key - YELLOW Introduction to Environmental...

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