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Determination of the thermodynamic dissociation constant of p ‐nitrophenol in {NaCl+EtOH+H 2 O} mixture by ultra‐violet spectrophotometry
Author(s) -
Yang JiaZhen,
Men DianYuan,
Guan XiuDan
Publication year - 1992
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.19920100303
Subject(s) - chemistry , dissociation constant , ionic strength , spectrophotometry , ultraviolet , nitrophenol , acid dissociation constant , ionic bonding , analytical chemistry (journal) , equilibrium constant , absorption spectroscopy , extrapolation , dissociation (chemistry) , stability constants of complexes , solvent , chromatography , aqueous solution , ion , organic chemistry , receptor , mathematics , quantum mechanics , catalysis , mathematical analysis , biochemistry , physics
The thermodynamic ionization constant K ° of p ‐nitrophenol in {10 mass% ethanol‐water} mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods: Debye‐Hückel extrapolation and polynomial approximation proposed by us in suitable buffer solution at constant ionic strength from 0.1 to 2.0 mol · kg −1 at 298.2 ± 0.2 K. The results from both methods are p K ° = 7.406 and 7.415, respectively. The effect of medium on the ultraviolet spectra of p ‐nitrophenol has been discussed.