A. at what ph are about 1/2 of the carboxyl groups ionized? ph = b. where does the amino acid have a net charge of +1? below ph 2.34 at ph = 2.34 at ph = 6.01 at ph = 9.69 above ph 9.69 c. at what point has enough base been added to react with 1/2 of the cooh groups? 1/2 of cooh reacted = equivalents oh− when 1/2 of cooh has reacted, the ph = d. at which ph value does the amino acid have the best buffering capacity? 1.53 10.5 2.34 6.01 3.00 9.00 e. what is the pi (isoelectric point)? pi =