Thermodynamic Properties of Aqueous Polyatomic Ions at Extreme Temperatures and Pressures

Abstract

Recently a theoretical treatment (J. Phys. Chem. B 2009, 113, 2398-2404) was developed for predicting the standard state thermodynamic properties of electrolytes up to and beyond the critical temperature of water (1273 K and at pressures up to 1000 MPa). In general, the model requires sufficient data at 298.15 K including the Gibbs free energy of hydration and at two higher temperatures to fix two constants for each electrolyte. This communication describes an extension of this "two constant" theory to thermodynamic properties of polyatomic ions for which no accurate data for the Gibbs free energy of hydration exits at 298.15 K.

Standard state thermodynamic properties of aqueous sodium perrhenate using high dilution calorimetry up to 598.15K

“…15 The resulting standard state partial molar heat capacities of NaReO 4 (aq) calculated from equation (11) and the parameters from table 3 are given in table 5: TABLE 3 Empirical parameters used to calculate the standard state enthalpies of solution at p sat from equation (8). a 1 À1.07518E+04 a 2 1.97861E+00 a 3 À1.98703EÀ03 a 4 À7.96380EÀ01 a 5 6.52909E+02 a 6 1.01097E+04 a 7 3.74633E+00…”

“…There is also one extremely important application of the data from sodium perrhenate solutions. The thermodynamic properties of NaCl(aq) [5], HReO 4 (aq) [7], and NaReO 4 (aq) from present study can be combined by ionic additivity to obtain data on the very important species, HCl(aq).…”

The standard state thermodynamic properties for completely ionized hydrochloric acid and ionization of water up to 523 K

“…where C p;2 ðHCl; aqÞ are from this study, C p;2 ðNaOH; aqÞ are from Simonson et al [35], C p;2 ðNaCl; aqÞ are from Djamali and Cobble [36], and C p ðH 2 O; lÞ are from the steam tables [18]. These D ioniz C p listed in table 5 and comparison with literature data are summarized in table 6 and figure 4.…”

Prediction of thermodynamic properties of aqueous electrolyte solutions using equation of state

“…Following relations are adopted from previous works to calculate the Gibbs free energy of hydration based on EOS: where the second term is the conversion from hypothetically ideal gaseous ions being hydrated to the hypothetically ideal 1 m aqueous solution . The reference molality is 1 molar ( = 1 mol/kg) and the standard state pressure (ideal gas) is 1 bar ( = 1 bar).…”

“…Their correlative model gives good results for partial molar volume as well the heat capacity but is not recommended for electrolytes near the critical point of water . Recently, Djamali, and Cobble developed a model for calculation of standard Gibbs free energy of ions hydration over a wide range of pressure and temperature . This model needs two adjustable parameters per each salt.…”