ECIV 350 Test Problems Questions with Complete Solutions

(Lecture 3-5) A water contains two nitrogen species. The concentration of NH3 is 30 mg/L NH3, and the concentration of NO3 - is 5 mg/L NO3 - . What is the total nitrogen concentration in units of mg N/L? Correct Answer-25.8 mg N/L (Lecture 3-5) What pH is required to reduce a high concentration of dissolved Mg2+ to 43 mg/L? Ksp for the following reaction is 10-11.16. Mg(OH)2(s) Mg2+ + 2OH Ksp = 10-11.16 Correct Answer-Ph=9.79 (Lecture 3-5) How long will it take the carbon monoxide (CO) concentration in a room to decrease by 99% after the source of CO is removed and the windows are opened? Assume the first-order rate constant for CO removal (due to dilution by incoming clean air) is 1.2/hr. No chemical reaction is occurring. Correct Answer-2.69 (Hw#1) 3-1 from Textbook. How many grams of NaCl would you need to add to a 1 L water sample (pH = 7) so the ionic strength equaled 0.1M? Correct Answer-5.8g What percentage of total ammonia (i.e., NH3 + NH4 + ) is present as NH3 at pH 7? pKa for NH4 = 9.3. NH4 + NH3 + H+ Correct Answer-05% (Hw#2) 4-6 from Textbook. Poorly treated municipal wastewater is discharged to a stream. The river flo