Problem 1. Arsenious acid is a weak acid HAsO2 <=====> H+ + AsO2- ; pKa = 9.22. If 1E-3 moles of a the herbicide NaAsO2 are added to 1 L of DI water at 25oC, what would be the resulting pH? Solve analytically. State and justify all assumptions.

Problem 2. A solution is made by adding 10-2 moles of (NH4)2CO3 to D.I. water to make one liter. a. Write the proton condition (i.e. proton balance equation (PBE)). b. Determine the pH of the solution by a graphical method on a pC vs. pH diagram.

Problem 3. What would be the pH of a soda water made by saturating distilled water with pure CO2 at 1 atm pressure?

Problem 4. Construct the pC-pH diagram for the carbonate system for a lake open to the atmosphere with a pCO2 of 10-3 atm.

Problem 5. Construct the pC-pH diagram for pore water in the soil where the pCO2 is 0.1 atm (due to microbial activity).

Instructor: Dr. Nikolaos P. Nikolaidis

Office: FLC Rm 318

e-mail: nikos@eng2.uconn.edu

Homepage: http://www.eng2.uconn.edu/cee/bio/Nikolaidis.html