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Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064

Abstract

SUYAMA, Emílio; PANIAGO, Eucler B.; CARVALHO, Sandra  and  COUTO, Bráulio R. G. M.. A robust calculation approach applied to the evaluation of hydrogen ion concentrations through potentiometric measurements in aqueous solutions. Quím. Nova [online]. 2001, vol.24, n.1, pp.5-9. ISSN 0100-4042.  http://dx.doi.org/10.1590/S0100-40422001000100002.

The data analyzed in this work were generated following the methodology developed by Molina et al.(J. Electroanal. Chem., 1979) for the calibration of a potentiometric system of measurement of hydrogen-ion concentrations resulting from neutralizations, at 25 oC, of acidic or alkaline solutions at constant ionic strength (0.1 mol.l-1) held with NaClO4. The observed data present a serious deviation in relation to the mathematical model derived from the Nernst equation, for pH values ranging from 3 to 11, where pH=-log[H+]. We show that the minimization of the sum of the absolute values of the residuals gives estimates that are not influenced by outlying values.

Keywords : calibration; potentiometric titration; hydrogen-ion concentrations [absolute error regression].

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