THE POTENTIOMETRIC MEASUREMENT OF ... - ACS Publications

(3) and of the zero adjustment knob of the meter, to make the potentiometer ... (Eq = equivalents added to the cell), the fundamental expression for E...
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FROM THE

CHEMISTRY DEPARTMENT OF FLORIDA STATE UNIVEBBITY]

T H E POTENTIOMETRIC MEASUREMENT OF ACID DISSOCIATION CONSTANTS AND pH I N THE SYSTEM METHANOL-WATER. pK, VALUES FOR CARBOXYLIC ACIDS AND ANILINIUM IONS A . L. BACARELLA, ERNEST GRUNWALD, H . P . MARSHALL, E. LEE PURLEE

AND

Received January 84, 1966

In recent years, acid dissociation constants have become increasingly important as tools in determining molecular structure and in solving questions of organic theory (1, 2). Many measurements have been made using a commercial pH meter and the cell glass electrode/solution X/KCI (sat ., aq.)/HgpC12-Hg

VI.

In this method of measurement it is convenient, by use of a buffer of known pH (3) and of the zero adjustment knob of the meter, to make the potentiometer scale direct-reading in pH units. However, the choice of a standard buffer solution requires some care since the method requires that the junction e.m.f. at the solut,ion X/I