• Potentiometric studies on the dissociation of gallic acid

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      https://www.ias.ac.in/article/fulltext/seca/051/04/0177-0188

    • Keywords

       

      Benzoic Acid; Gallic Acid; Dissociation Constant; Thermodynamic Function; Monocarboxylic Acid

    • Abstract

       

      Dissociation of gallic acid at different temperatures in the range 300–380 Å was investigated using glass and calomel electrodes. Applying modified Debye-Huckel equation the thermodynamic dissociation constantK was calculated. The variation ofK with temperatureT appeared to follow:—$$ - lnK = \frac{A}{T} + B + CT$$ where the constantsA, B andC for gallic acid were 84·11, 5·59 and 14·29 ×10−3 respectively. From these, the thermodynamic functionsΔF,ΔH,ΔS andΔCp were computed. The effect of substitution of three hydroxyl groups in the nucleus of benzoic acid onpK andΔF was discussed. The radius of the anion of gallic acid was computed from the calculated values ofΔH; it corresponded to 0·78 Å.

    • Author Affiliations

       

      N A Ramaiah1 R K Chaturvedi1

      1. Department of Physical Chemistry, National Sugar Institute, Kanpur
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