Ass 1_sol

# Ass 1_sol - CIVL 242 Assignment 1 Solution 1 Calculate the...

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1 CIVL 242 Assignment 1 Solution 1. Calculate the hardness of a water sample containing 20 mg/L K + , 30 mg/L Ca 2+ , 50 mg/L Mg 2+ , 100 mg/L Cl - , and 40 mg/L SO 4 2- . Key point: Hardness: A total concentration of all divalent metallic ions (M 2+ ), such as Ca 2+ , Mg 2+ , Fe 2+ , Cu 2+ , and etc., expressed in mg/L as CaCO 3 . Solution : Ions concerned are Ca 2+ and Mg 2+ Hardness × = + + i M i i q M H 50 2 2 mg/L as CaCO 3 2 2 i i M MW q + = 2 40 20 2 Ca q + == 2 24.4 12.2 2 Mg q + 3 30 50 50 279.92 / as CaCO 20 12.2 Hm g L ⎛⎞ =+ × = ⎜⎟ ⎝⎠ 2. Calculate the TN of a solution containing 30 mg/L glycine (C 2 H 5 O 2 N), 100 mg/L NaNO 3 and 50 mg/L NH 4 Cl. Key point: Total nitrogen (TN): A total concentration of ammonia nitrogen, organic nitrogen, nitrate nitrogen and nitrite nitrogen, expressed in mg/L as N. Solution: Compounds concerned are C 2 H 5 O 2 N, NaNO 3 and NH 4 Cl

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2 N as L mg TN / 15 . 35 5 . 35 4 1 14 14 50 3 16 14 23 14 100 14 2 16 5 1 2 12 14 30 = + × + × + × + + × + + × + × + × × = 3. A water with a pH 10.3 contains HCO 3 - and CO 3 2- at 6.1 and 6.0 mg/L, respectively. What is its total alkalinity in mg/L as CaCO 3 ? Key point: Alkalinity: The measure of the capacity of a water to neutralize acids, in other words, to absorb hydrogen ions without significant pH change, expressed in mg/L
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## This note was uploaded on 09/13/2011 for the course CIVL 242 taught by Professor Gh during the Fall '09 term at HKUST.

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Ass 1_sol - CIVL 242 Assignment 1 Solution 1 Calculate the...

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