Artículo
Abstract:
A modified laboratory experiment for undergraduate students is presented to evaluate the effects of the ionic strength, I, on the equilibrium concentration quotient, K c, of the acid-base indicator bromcresol green (BCG). The two-step deprotonation of the acidic form of the dye (sultone form), as it is dissolved in water, yields suitable hydronium concentration in the solution to carry out the experiment successfully and avoids the use of any buffer solution to fix the hydronium concentration of the media. The 95% confidence interval for the slope parameter (-2.08 ± 0.13), obtained from the linear fit of pK c versus √I/ (1 + 2.30√I) plot, contains the theoretical value of -2.04 predicted by the Debye-Hückel extended law. From the intercept, a value for the equilibrium dissociation constant of BCG, pK = (4.91 ± 0.02), is obtained, showing a reasonable agreement with literature data. The simplification makes it possible for students to complete the experiment in the course of an ordinary 3-h laboratory session. © 2012 The American Chemical Society and Division of Chemical Education, Inc.
Registro:
| Documento: | Artículo |
| Título: | A simplified undergraduate laboratory experiment to evaluate the effect of the ionic strength on the equilibrium concentration quotient of the bromcresol green dye |
| Autor: | Rodríguez, H.B.; Mirenda, M. |
| Filiación: | Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pab. II, C1428EHA, Buenos Aires, Argentina INQUIMAE, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pab. II, C1428EHA, Buenos Aires, Argentina Gerencia de Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, 1650 San Martín, Pcia. de Buenos Aires, Argentina |
| Año: | 2012 |
| Volumen: | 89 |
| Número: | 9 |
| Página de inicio: | 1201 |
| Página de fin: | 1204 |
| DOI: | http://dx.doi.org/10.1021/ed200733k |
| Título revista: | Journal of Chemical Education |
| Título revista abreviado: | J Chem Educ |
| ISSN: | 00219584 |
| CODEN: | JCEDA |
| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219584_v89_n9_p1201_Rodriguez |
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Citas:
---------- APA ----------
Rodríguez, H.B. & Mirenda, M. (2012) . A simplified undergraduate laboratory experiment to evaluate the effect of the ionic strength on the equilibrium concentration quotient of the bromcresol green dye. Journal of Chemical Education, 89(9), 1201-1204.http://dx.doi.org/10.1021/ed200733k
---------- CHICAGO ----------
Rodríguez, H.B., Mirenda, M. "A simplified undergraduate laboratory experiment to evaluate the effect of the ionic strength on the equilibrium concentration quotient of the bromcresol green dye" . Journal of Chemical Education 89, no. 9 (2012) : 1201-1204.http://dx.doi.org/10.1021/ed200733k
---------- MLA ----------
Rodríguez, H.B., Mirenda, M. "A simplified undergraduate laboratory experiment to evaluate the effect of the ionic strength on the equilibrium concentration quotient of the bromcresol green dye" . Journal of Chemical Education, vol. 89, no. 9, 2012, pp. 1201-1204.http://dx.doi.org/10.1021/ed200733k
---------- VANCOUVER ----------
Rodríguez, H.B., Mirenda, M. A simplified undergraduate laboratory experiment to evaluate the effect of the ionic strength on the equilibrium concentration quotient of the bromcresol green dye. J Chem Educ. 2012;89(9):1201-1204.http://dx.doi.org/10.1021/ed200733k
