PHCL 343 Biochemical Foundations of Therapeutics
pH problem set - - no credit

1. Acetic acid (pKa 4.76) and sodium hydroxide are combined in 100 ml of solution. The concentration of all forms of acetic acid combined is 0.1 M and the final pH is 5.
(a) What is the ratio of the proton donor and proton acceptor forms in this solution?
(b) What is the concentration of sodium?
(c) What molecule is the proton acceptor and what molecule is the proton donor?

2. You have 20 ml of 5 M phosphoric acid and 80 ml of 2 M sodium hydroxide. The pKa values for phosphoric acid are 2.12, 7.21, and 12.67.
(a) What is the pH of the 20 ml solution of phosphoric acid before it is mixed with the sodium hydroxide?
(b) What is the pH of the mixture?
(c) What molecule is the proton donor and what molecule is the proton acceptor in the mixture?

3. (a) What are the molar concentrations of the proton donor and proton acceptor species when 1 mM glycine is dissolved in water at pH 9?
(b) Give the structures of the proton donor and proton acceptor and label them as such. The pKa values for glycine are 2.34 and 9.6.
(c) Draw a titration graph of glycine with NaOH and indicate the structures and relative amounts of the various ionic forms of glycine that are present for each appropriate pH range.

4. You have a solution of leucine at 0.1 gram in 100 ml. Give (a) the molar concentrations and (b) the structures of each ionic form of leucine that will be present at pH 7.4. The pKa values for leucine are 2.36 and 9.6.