o-phthalic acid as a standard substance for calibrations of hydrogen ion concentrations with a glass electrode
✍ Scribed by J.A. Kennedy; H.K.J. Powell; M.C. Taylor
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 516 KB
- Volume
- 147
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
o-Phthalic acid is proposed as a standard substance for buffer solutions of known hydrogen ion concentration (I < 0.2 M KCl, p[H+] = 3.0-5.4, 25°C). Its crystallinity, purity and slightly wider buffer range afford advantages over acetic acid. Empirical relationships between measured pH (pH,) and calculated [H'] were derived for sequences of buffer solutions at several ionic strengths: pH, = Mp[H+] + C. These calibration lines were parallel and of unit slope as required by theory. A table of p[H+] values for Ophthalic acid buffer solutions at Z = 0.1 M (KCl) is presented and the method of calculation of p[ H+] values for a buffer series generated by additions of potassium hydroxide is outlined.