Apparent and partial molar heat capacities and volumes of aqueous HClO₄ and HNO₃ from 10 to 55 °C

Abstract

Apparent molar heat capacities and volumes of aqueous solutions containing HClO4 and HNO3 have been determined from 10 to 55 °C. The temperature dependences of the standard state heat capacities and volumes of ClO4− (aq) and NO3− (aq) from 10 to 55 °C were found to be well represented by the following equations:[Formula: see text]Combination of the experimental results with semiempirical equations for ion–solvent interaction has led to predictions of the standard state volumes and heat capacities for these ionic species at higher temperatures. Keywords: heat capacities, volumes, nitric acid, perchloric acid.

Apparent Molar Heat Capacities and Volumes for NpO2C1O4(aq) to 100 °C: Calculation of the Temperature Dependence of the MOn+ 2(VI/V) Couple

“…Recently we reported heat capacity and density measurements for HC104(aq) to 100°C. In the same paper [7], we reported an equation based on our work and that of Hovey et al [13,14] (10°C to 55°C). That equation has been used in the present set of calculations for the apparent molar heat capacities.…”

“…That equation has been used in the present set of calculations for the apparent molar heat capacities. The equation for the apparent molar volumes for HC104(aq) used here (as described below, see also Table 4) was derived from the same data sets [7,13,14] even though there are some small systematic differences [7]. The density data in the present work are not sufficiently consistent that the calculated values of Vj -t. for the dioxoactinide Perchlorates would be sensitive to these differences.…”

“…were fitted by the method of least squares to the equally weighted apparent molar volumes for HC104(aq) [7,13,14] and U02(C104)2(aq) (values from Hovey et al [2] and from the present work). The parameter b is an arbitrary constant in the Pitzer equations and is assigned the value 1.2 kg"^ • mol''^; I is the molal ionic strength; T is the Kelvin temperature; Av is the theoretical limiting Debye-Hückel slope for partial molar volumes [17].…”

Thermodynamic properties of aqueous calcium nitrate {Ca ( NO3)2}to the temperature 373 K including new enthalpy of dilution data

“…As the published data for Ca(NO 3 ) 2 (aq) tend to be at very high molalities, particularly above T = 298.15 K, Pitzer ion-interaction parameters which operate most strongly at low ionic strengths (e.g., β (2) (39,40) HCl, (43) and HNO 3 : (44,45) …”

“…Hovey and Hepler (44) determined C o p,φ (HNO 3 ) and V o φ (HNO 3 ) to T = 328 K and Clegg and Brimblecombe (45) (36) and (49). Curves calculated at T = 332 K and T = 341 K are undistinguishable from the curve at T = 323 K.…”