POTENTIOMETRIC TITRATION OF HYDROCHLORIC ACID DILUTE SOLUTION USING A METROLOGICAL APPROACH

P. P. Borges, I. C. Fraga, A. P. Ordine, H. C. Carnaval, B. S. Rossini, J. C. Dias

Abstract

Primary methods of measurement are essential in the realization of the SI units. In 1995, the CCQM (Comité Consultatif pour la Quantité de Matière) identified titrimetry as a primary method of measurement. Titrimetry is a method that has wide range of applications for amount of substance measurements and can be applied at primary level and at working level depending on the uncertainty values. The aim of this work is to present the results of potentiometric titration of a dilute solution of hydrochloric acid (HCl). The potentiometric titration method was carried out with the solution addition controlled gravimetrically. The results were accurate and HCl concentration of (0.010042 ± 0.000112) mol kg^-1, <i>k</i> = 2 for approximately 95% confidence level was obtained. The molality determination of HCl solution is a prerequisite for the use of a Harned cell, the primary method for the realization of pH measurement. The HCl solution is used in the pH primary system at Inmetro to obtain accurate value of the silver-silver chloride electrode potential. This standard potential is very important for the correct measurement of pH to certificate pH buffer.

Keywords

potentiometric titration, gravimetry, hydrochloric acid

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PWC-2006-TC8-012u.pdf

DOI

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IMEKO TC

TC8 - Traceability in Metrology

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