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  Home > JCE Print > Journal of Chemical Education > Issues > 2000  > September  >
In the Classroom
Easy Derivation of pH Is Approxiimately Equal To (pKa1 + pKa2) / 2 Using Autoprotolysis of HA-: Doubtful Value of the Supposedly More Rigorous Equation

Stephen J. Hawkes
Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003

Cover
September 2000
Vol. 77 No. 9
p. 1183
Abstract
[H+]2 Is Approxiimately Equal To Ka1Ka2 can be derived in only two lines by recognizing that the principal reaction in a solution of HA- is its autoprotolysis. The supposedly rigorous equation derived in many texts gives pH values that are no more reliable.

See Letter re: this article.
More Information
*  Citation
 Hawkes, Stephen J. J. Chem. Educ. 2000 77 1183.
*  Keywords
 Acid-Base Chemistry; Equilibrium
*  History
 Created:
Last Updated:		 August 29, 2000
June 22, 2005
Link to Letter added (April 2004).
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