Determination of the thermodynamic dissociation constant of p‐nitrophenol in {NaCl+EtOH+H₂O} mixture by ultra‐violet spectrophotometry

Abstract

The thermodynamic ionization constant K' of pnitrophenol in { 10 mass% ethanol-water) mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods:Debye-Huckel extrapolation and polynomial approximation proposed by us in suitable buffer solution at constant ionic strength from 0.1 to2.0 mo!. k g l at 298.2 k0.2 K. The results from both methods are pK' =7.406 and 7.415, respectively. The effect of medium on the ultraviolet spectra ofp-nitrophenol has been discussed.