Thermodynamics for ionization of water at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa: apparent molar volumes of aqueous KCl,KOH, and NaOH and apparent molar heat capacities of aqueous HCl,KCl, KOH,and NaOH

Apparent molar volumes V_φof aqueous KCl, KOH, and NaOH and apparent molar heat capacities C_{p, φ}of aqueous HCl, KCl, KOH, and NaOH have been determined at the pressure p =  0.35 MPa, and at molalities 0.015 ?m / mol · kg ^? 1? 0.5. Densities were measured using a vibrating-tube densimeter (DMA 512, Anton Paar, Austria) at temperatures 278.15 ?T / K? 368.15. These values were used to calculate the apparent molar volumes. A fixed-cell, differential-output, power-compensating, temperature-scanning calorimeter (NanoDSC model 6100, Calorimetry Sciences Corporation, Spanish Fork, UT, U.S.A.) was used to measure the heat capacities of the same solutions at temperatures 278.15 ?T / K? 393.15. Results were fitted by using equations that describe the surfaces (m, T, V_φ) and (m, T, C_{p, φ}). Using these equations, we have calculated the surfaces (m, T, Δ_rV_m), (m, T, Δ_rC_{p, m}), (m, T, Δ_rH_m), (m,T , p Q_a), and (m, T,Δ_rS_m ) for the ionization of water in the presence of combinations of the above electrolytes. The last three surfaces were calculated by integration using our (m,T , Δ_rC_{p, m}) surface and literature values for the molality dependence of Δ_rH_mand pQ_a at T =  298.15 K.