Apparent molar volumes and heat capacities of aqueous acetic acid and sodium acetate at temperatures fromT = 278.15 K toT = 393.15 K at the pressure 0.35MPa

Karine Ballerat-Busserolles (1, 2) , Todd D. Ford (2) , T. G. Call (2) , Earl M. Woolley (2)

1 LTIM - Thermodynamique et Interactions Moléculaires
2 DCB - Department of chemistry and Biochemistry

Apparent molar volumes Vφand heat capacities Cp , φof aqueous solutions of acetic acid (CH3CO2H) and sodium acetate (CH3CO2Na) , and Cp , φfor hydrochloric acid (HCl) and sodium hydroxide (NaOH) were determined at temperatures from T = 278.15 K to T = 393.15 K at the pressure 0.35MPa. Apparent molar volumes were obtained from density measurements using an Anton Paar vibrating-tube densimeter (DMA 512, Anton Paar, Austria). Heat capacities were obtained using a fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC model 5100, Calorimetry Sciences Corporation, Provo, UT). Infinite dilution partial molar volumes Voand heat capacities Cpowere obtained over the range of temperatures by extrapolation to m = 0 of the fitted surfaces (Yφ, T , m). The volume results were combined with values of Vofrom the literature for aqueous NaCl, HCl, and NaOH to obtain ΔrVmofor ionization of acetic acid. Measured values of Cp , φwere extrapolated to m = 0 for HCl(aq) and NaOH(aq) and used to obtain values of ΔrCp , mofor ionization of CH3CO2H(aq). The values of ΔrVmoand ΔrCp , moallow the determination by integration of the equilibrium constant Kaand other thermodynamic properties for ionization of CH3CO2H(aq) from T = 278.15 K to T = 393.15 K at the pressure 0.35MPa.

Mots clés: Apparent molar volumes; Apparent molar heat capacities; aqueous acetic acid; aqueous sodium acetate

Domaines: Chimie théorique et/ou physique

Karine Ballerat-Busserolles, Todd D. Ford, T. G. Call, Earl M. Woolley. Apparent molar volumes and heat capacities of aqueous acetic acid and sodium acetate at temperatures fromT = 278.15 K toT = 393.15 K at the pressure 0.35MPa. Journal of Chemical Thermodynamics, 1999, 31, pp.741-762. ⟨10.1006/jcht.1999.0484⟩. ⟨hal-00560878⟩