Hammett acidity function
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Hammett acidity function[′ham·ət ə′sid·əd·ē ‚fəŋk·shən]
An expression for the acidity of a medium, defined as h0= KBH +[BH +]/[B ] , where KBH +is the dissociation constant of the acid form of the indicator, and [BH +] and [B ] are the concentrations of the protonated base and the unprotonated base respectively.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.