Standard values for pH measurements from 5 to 55°C

CHED 211

Cole E. Denton, cdenton@drury.edu, Sean R. LeNoue, slenoue@drury.edu, Samantha D. Egbert, segbert@drury.edu, Lakshmi N. Roy, lroy@drury.edu, and Rabindra N. Roy, rroy@drury.edu. Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Ave., Springfield, MO 65802
Standard values of pH for the doubly charged amino acids AMPSO and CHES have been determined from 5 to 55°C, including 37°C. The electromotive-force measurements have been made using the cell without liquid junction: Pt; H2 (g, 1 atm) | AMPSO (m1) + NaAMPSOate (m2) + NaCl (m3) | AgCl, Ag. The results of the pH will be compared with those for other protonated bases of similar structure. The discussion will be made in terms of its applicability in the biomedical field. Conventional pH values for two buffers, AMPSO and CHES with solution compositions: m1 = m2 = 0.05, m3 = 0.00; m1 = m2 = 0.08, m3 = 0.00; and m1 = m2 = m3 = 0.08 mol•kg-1 (I = 0.16 mol•kg-1, isotonic saline solution) have been calculated using Bates-Guggenheim convention and the Pitzer treatment of the single ion activity coefficient of the chloride ion.
 

Undergraduate Research Poster Session: Biochemistry
2:30 PM-4:30 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Poster

Division of Chemical Education

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006