Dissociation Quotients of Succinic Acid in Aqueous Sodium Chloride Media to 225°C

Authors

Richard Kettler, University of Nebraska-LincolnFollow
Donald A. Palmer, University of Nebraska, Lincoln
David J. Wesolowski, Oak Ridge National Laboratory

Date of this Version

1995

Comments

Published in Journal of Solution Chemistry, Vol. 24, No.1, 1995

Abstract

The first and second molal dissociation quotients of succinic acid were measured potentiometrically with a hydrogen-electrode, concentration cell. These measurements were carried out from 0 to 225"C over 25 ° intervals at five ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The dissociation quotients from this and two other studies were combined and treated with empirical equations to yield the following thermodynamic quantities for the first acid dissociation equilibrium at 25°C: logK_1a = -4.210±0.003; Δ H_1̊a = 2.9±0.2 kJ-mol ^{- 1} ; ΔS_1̊a = -71±1 J-mol ^{- 1} -K ^-1; and ΔC_p̊,1a = -98±3 J-mol ^-1 -K ^-1; and for the second acid dissociation equilibrium at 25°C: logK_2a = -5.638±0.001; ΔH_å = -0.5±0.1 kJ-mol ^-1 ; ΔS_2̊a = -109.7±0.4 J-mol ^-1 -K ^-1; and ΔC_p̊,2a = -215±8 J-mol^-1-K^-1.