Resumo

CANEZ-CARRASCO, María Guadalupe et al. Conductimetry and titrations: When? why? what for?. Educ. quím [online]. 2011, vol.22, n.2, pp.166-169. ISSN 0187-893X.

The conductimetric and potentiometric measurements detect the changes experimented by the system following the course of neutralization reactions in colored electrolytic dissolutions allowing accurate detection of equivalence point. Moreover, wines are susceptible to adulteration of different types, from dissolution with water to more complex as the addition of mineral acids. The conductimetric and potentiometric titrations are very useful in investigating the addition of mineral acid to wines. This experimental work allowed comparing the applicability and utility of the conductimetric and potentiometric measurements. Furthermore, some red wine samples were analyzed obtaining, on one hand, the graphical representation of the variation of the conductivity of the dissolution according to the volume of the titrant dissolution; on the other hand, the graphical representation of the variation of the pH according to the volume of the titrant dissolution using the analytical method of the first derivative. The obtained results in the visual assessments, conductimetric and potentiometric showed the following averages of 5,35 ± 0,06 g/L (c.v.=1,12%); 5,16 ± 0,03 g/L (c.v.= 0,05%); and 7,99 ± 0,06 g/L (c.v.= 0,75%) of total acidity expressed as tartaric acid, respectively. The conductimetric monitoring system showed a higher sensitivity in the determination of total acidity in diluted and colored samples.

Palavras-chave : conductimetry; potenciometry; titrations; wines.

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