NIST-JANAF Thermochemical Tables. II. Three Molecules Related to Atmospheric Chemistry: HNO3, H2SO4, and H2O2

Abstract

The structural, spectroscopic, and thermochemical properties of three polyatomic molecules with internal rotation—HNO3(g), H2SO4(g), and H2O2(g)—have been reviewed. Three revised ideal gas thermodynamic tables result from this critical examination. The revisions involved the consideration of new spectroscopic information and the use of theoretical results to model the internal rotation in the H2SO4 molecule. Compared to previous calculations, the entropies at 298.15 K are unchanged for HNO3 and H2O2, but the high temperature values (T>4000 K) are significantly different. As for H2SO4, its thermodynamic functions differ significantly from values calculated earlier.

Gas phase dissociation of H2SO4: A computational study

“…As expected by the predicted energy for the reaction (1) reported in table 4, the agreement between our calculated enthalpy of formation at 0 K for H 2 SO 4 (g) and the assessed value by Dorofeeva et al [33] is poor. However, it should be mentioned that in their work Dorofeeva tested a variety of computational methods to calculate the enthalpy of formation of the gaseous sulfuric acid and found in all cases a smaller value compared to experiments.…”

“…The predicted vibrational frequencies are in satisfactory agreement with the available experimental data. In particular for H 2 O, SO 3 , H 2 SO 4 the average deviation is 5.0% [35], 6.2% [35] and 4.4% [33], respectively. For the hydrated complexes the only partial comparison can be made for H 2 SO 4 (H 2 O) with IR-matrix isolation measurements by Givan [14].…”

“…The used G.e.f. polynomial formula is the following: Also the calculated coefficients of a similar polynomial fit of the H 2 SO 4 (g) Gibbs energy functions assessed in [33] are shown in table 3.…”

“…For the condensed species (H 2 SO 4 (l), H 2 O(l)) data were taken from [32]. Among all the gaseous molecules, apart the well known H 2 SO 4 (g) [33], SO 3 (g) [34], SO 2 (g) [34], O 2 (g) [32], H 2 O(g) [32], SO(g) [32] and H 2 S(g) [32], also many other minor gas species were considered in the database: H, HO, HSO, SOH, HO 2 , HS, H 2 , H 2 SO, HSOH, H 2 O 2 , H 2 S 2 , O, O 3 , S, S 2 , S 3 , S 4 , S 5 , S 6 , S 7 , S 8 ; their thermodynamics were taken from [32]. In the thermodynamic calculations also the gaseous coordination complexes SO 3 2 have been considered.…”

In situ (α-Al2O3+ZrB2)/Al composites with network distribution fabricated by reaction hot pressing

“…According to the published thermodynamic data [17], the possible reactions and their accompanying free-energy changes in the Al-ZrO 2 -B system can be written as the following equations.…”