1. Look up and write down the equilibrium constant for the reaction:

 H₂PO₄^- = H⁺+ HPO₄^-2

_{2. 12.5 mL of 0.124 M NaOH mixed with 2 mL of 0.147 M HCl; pH = _______.}

_{3 Calculate the pH of a 0.05 M ethanolamine solution. (Kb = 2.8x10}^-5

<sup>4. For each of the following titration curves calculate the equivalent weight of the acid.  Then match the acid with the curve.  Indicate the pKa's on the titration curve. 250 mg of the acid are titrated with 0.1000 N NaOH.

Acid                        MW          pKa's

Ammonium sulfate           132     9.26(both NH4+ ions)
Citric Acid Hydrate          210  3.09, 4.75, 5.40
Maleic Acid                      116   1.83, 6.07
Oxalic acid dihydrate        126   1.23, 4.19
Phthalic Acid                    166   2.89, 5.51
Serine                                 76     9.15
Citric acid monohydrate MW = 210 pKa's 3.09,4.75, 5.41</sup>