Key points are not available for this paper at this time.
The ionic speciation and the optical properties of aqueous H 2 SO 4 have been investigated as a function of temperature and acid concentration by spectroscopic techniques. FT-Raman spectra have been obtained of 1.43−44.04 molal (12−81 wt %) aqueous H 2 SO 4 in the temperature region from 300 to 220 K. The degree of dissociation of the second dissociation step in aqueous H 2 SO 4 (α 2: HSO 4 - ⇄ H + + SO 4 2- ) is derived from the relative intensities of the HSO 4 - Raman bands around 1050 cm -1 versus the SO 4 2- band around 980 cm -1, and a polynomial parametrization of α 2 is presented. FT-IR specular reflectance spectra are obtained of 6.46−44.04 molal (38−81 wt %) aqueous H 2 SO 4 in the temperature region from 300 K to as far down as possible before crystallization by freezing occurred. The complex index of refraction is obtained from the IR reflectance spectra by the use of the Kramers−Kronig transformation, and the importance of including far-infrared data in the transformation is demonstrated. A revised parametrization of the density of aqueous sulfuric acid is given and an interpolation algorithm for obtaining the complex index of refraction of aqueous sulfuric acid solutions as a function of acid weight fraction and temperature is presented.
Myhre et al. (Sat,) studied this question.