HOMEWORK #3:

1. (A&P 4.1)  Given the following water from Rajsthan, India, in mM L^-1: 

   pH                   7.3                   
   NO₃^-                7.8
   HCO₃^-              14.8
   SO₄^2-                5.20
   Cl^-                    17.4
   F^-                     0.356
   Ca²⁺                 0.675
   Mg²⁺                0.785
   Na⁺                  47.9
   K⁺                    0.150

   a)      Calculate the saturation state of the water for fluorite without making any correction for ionic strength or complexes.

   b)       Do the same (calculate saturation state) but correct for ionic strength.

    

   c)    we will do the same thing using PhreeqC in the next recitation

2. Is the following reaction exothermic at STP (what is ΔH)?

Reaction:  H₂S  +  O₂  à 2H⁺ + SO₄^2-

3. (S&J 4.1) Calculate the pH of the following perchloric acid, HClO₄, solutions

            a) 10^-3 M

            b) 10^-8 M

4. Find the equilibrium constant, K_w, at 25 ^oC and 40 ^oC for the following reaction

                            H₂O ßà H⁺ + OH^-

          What is the pH of neutral water at 40 ^oC

    

 Spreadsheet.  Calculate the ionic strength of your spreadsheet waters.  Give activity coefficients and activities for the major constituents (using either Guntelberg or Debye-Huckel approximations).  Don’t forget to give any thermodynamic data used and show example calculations.