Spectrophotometric measurement of the first dissociation constants of carbonic acid at elevated temperatures

Sung Nam Park, Chang Shik Kim, Myung Hwa Kim, In Ja Lee, Keon Kim

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24 Citations (Scopus)

Abstract

Using 2,5-dintrophenol as an optical indicator, the pH of a carbonate buffer solution was spectrophotometrically measured at temperatures from 25 to 175°C. The pH values measured in this study were utilized to determine the first dissociation constant of carbonic acid at various temperatures. The result was pK1 = -1234.4 + 68608/T + 193.37 ln T - 0.16423T - 3746800/T2 where T is in Kelvin. By using this fitted function, the thermodynamic functions for carbonic acid at 25°C were calculated. When the dissociation reaction of carbonic acid was rewritten as an isocoulombic reaction, the plot of log KOH against 1/T was approximately linear over the temperature ranges studied, as in other isocoulombic reactions.

Original languageEnglish
Pages (from-to)1421-1425
Number of pages5
JournalJournal of the Chemical Society - Faraday Transactions
Volume94
Issue number10
Publication statusPublished - 1998 May 21

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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