Assign:

1. What is the pH of a 0.015 M monoprotic acid whose Ka is 5.7 x 10-4 ?Use approximation test to determine how to proceed in solving the problem.

2. What is the pH of a buffer that is 0.1M Na2HPO4 and 0.15 M KH2PO4? Ka 6.2 x 10-8

3. Solve for the pH of a buffer that is 0.15 M NH3/0.35 M NH4Cl. Kb = 1.8 x 10-5

What is the change if the following impurities are added to the above: a) 0.02 M HCl b) 0.05 M NaOH

4. A diprotic acid H2A has the following ionization constants: Ka1 = 1.1 x 10-3 Ka2 = 2.5 x 10-5

To prepare a buffer solution with a pH of 5.8, which will you choose? Why?a) NaHA/H2A b) Na2A/NaHA

5. How would you prepare a buffer solution of bicarbonate/carbonic aicd with a pH of 9.2 Ka1 = 4.2 x 10-7 Ka2 = 4.8 x 10-11