Alkalinity Expressed as ph and Henry’s Law Questions

## Acids & Bases II, Titrations.

What is the alkalinity and pH of a solution containing 0.0001MNaHCO3after it has reached an equilibrium with an underground atmosphere containing CO2at a partial pressure of 0.01 atm?
2.Some groundwaterwater is equilibrated with PCO2= 10-2.0atm. The solution needs to be adjusted to pH 8.0 by the addition of NaOH or HCl. What, in fact, would need to be added and in what dosage (mg/l)?
3. A water is characterized by a pH of 8.3and an alkalinity of 25mg/l as CaCO3. It is desired to increase the alkalinity to 125mg/l as CaCO3 while not changingpH.Describe two possible means to accomplish this objective by the addition/removal of chemical(s). Summarize initial and final water characteristics as well as chemical type(s) and dosage(s).
4.A NHstream flows at2.0 MGDwith a pH of 6.2 and a total alkalinity of only 50mg/l as CaCO3. Aprocess wastewater discharge(1.0MGD and pH of 2.5) is added to the NHstream.
(a) Will the resulting pH of mixing thewastewater discharge with the streamresult in the pH falling below 6.0?

(b) If so, describe at least two different treatment scenarios that could be used to raise the mixture pH to a desired target of 8.0.Please provide both the chemical(s) and dosages required.

5.Develop a titration curve for a 0.01 MH2CO3solution using NaOH as the titrant. At what pH(s) would the solution be most resistant to pH changes?Hint: Use Excel to develop af vs pHgraph following the equation provided in the class notes.

6.A buffer solution has been prepared by adding 0.2 Mof HAc and 0.1 Mof NaAc. The pH of the solution has been adjusted to 5.0 by addition of NaOH. How much additional NaOH (mg/l) is required to increase the pH to 5.3?(Try to solve this problem using the Buffering Capacity Index equation)

7.A 1-liter solution contains 100 mg of HCl. Calculate the following:(a)Initial pH(b)pH after addition of 1 ml of 1.0 N NaOH.(c)pHafter addition of 2 ml of 1.0 N NaOH(d)pH after addition of 3 ml of 1.0 N NaOH