ChemInform Abstract: Electrical Conductance and Viscosity of Concentrated H2SO4/H2O Binary Systems at Low Temperatures: Correlation with Phase Transitions.

Abstract

Electrical Conductance and Viscosity of Concentrated H2SO4/H2O Binary Systems at Low Temperatures: Correlation with Phase Transitions.-The temp. and concentration dependence of the density, electrical conductivity, and viscosity of concentrated H2SO4/H2O systems containing above 66 wt.% H2SO4 are determined in the subambient temp. region. The temp. dependence of the transport properties can be adequately described by the power-law equation. Structural changes in the H2-SO4/H2O system observed around 83-85 and 92-94 wt.% H2SO4 corresponds to formation of H2SO4·H2O (at 84.48 wt.% H2SO4) and the eutectic between H2SO4·H2O and H2SO4 (at 93.8 wt.% H2SO4), respectively. A direct correlation between the viscosity-concentration curve and the phase diagram of the H2SO4/H2O system exists above . apprxeq.75 wt% H2SO4. -(DAS, A.; DEV, S.; SHANG-PLIANG, H.; NONGLAIT, K. L.; ISMAIL, K.; J.

Dynamics in Glass Forming Sulfuric and Nitric Acid Hydrates

“…However, some stoichiometric compositions, particularly in the sulfuric acid system, are good glass formers, too. Glass forming aqueous sulfuric acid solutions were already studied by specific heat, , viscosity, − conductivity, − as well as diffusion measurements. − Apart from transport coefficients, also vibrational properties − and structural aspects , of these hydrates were examined. Owing to a generally much stronger crystallization tendency as compared to the sulfuric systems, the supercooled and glassy states of the nitric acid hydrates were studied much less. ,− The calorimetric glass transition temperatures T g,cal of the presently investigated acid hydrates are in the range from 153 to 164 K. , Glass transitions as well as transport properties were also investigated for various other acid hydrates. ,− Particular attention was directed to phosphoric and phosphorus acids that hold promising potential for use in solid electrolyte devices. − …”