Diffusion Coefficients in Cold Sulfuric Acid Solution

Klenø, J. G.; Kristiansen, M.; Nielsen, Claus J.; Pedersen, Erik; Williams, Leah R.; Pedersen, Torben Graves

doi:10.1021/jp0106754

Cited by 9 publications

(15 citation statements)

References 10 publications

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“…6,38,39 They are formally 0.23-0.30 mole fraction D 2 SO 4 , but the acid ionizes extensively and consists of D 2 O, D 3 O + , DSO 4 -, and SO 4 2-. 6,40 Sum frequency generation experiments using H 2 SO 4 solutions indicate that the interfacial region is composed of ion pairs or neutral molecules with no dangling OH bonds.…”

Section: Properties Of Pure and Butanol-doped Sulfuric Acid Solutionsmentioning

confidence: 99%

Evaporation of Water through Butanol Films at the Surface of Supercooled Sulfuric Acid

2005

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The evaporation of water was monitored from 60, 64, and 68 wt % D(2)SO(4) at 213 K containing 0-0.18 M 1-butanol. Measurements were performed in vacuum using a mass spectrometer to record the velocities and relative fluxes of the desorbing D(2)O. In addition, the surface activity of butanol in the acid was characterized by hyperthermal argon atom scattering in conjunction with surface tension and butanol evaporation measurements. The segregated butyl species reach surface concentrations of approximately 4 x 10(14) cm(-2) (approximately 80% surface coverage) at 0.18 M bulk concentration. We find that the butyl films do not impede the evaporation of D(2)O from the acid to within the 5% uncertainty of the measurements. This result implies that small, soluble surfactants such as butanol form porous films that will not alter the growth or shrinkage of supercooled sulfuric acid droplets in the atmosphere.

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Section: Properties Of Pure and Butanol-doped Sulfuric Acid Solutionsmentioning

confidence: 99%

Evaporation of Water through Butanol Films at the Surface of Supercooled Sulfuric Acid

2005

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“… a Calculated from ref . b Calculated from refs and . c Sum of all surface hexyl species, determined from surface tension measurements in refs and .…”

Section: Properties Of Bare and Hexanol-doped Sulfuric Acidmentioning

confidence: 99%

Evaporation of Water and Uptake of HCl and HBr through Hexanol Films at the Surface of Supercooled Sulfuric Acid

2006

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Vacuum evaporation and molecular beam scattering experiments have been used to monitor the loss of water and dissolution of HCl and HBr in deuterated sulfuric acid at 213 K containing 0 to 100 mM hexanol. The addition of 1-hexanol to the acid creates a surface film of hexyl species. This film becomes more compact with decreasing acidity, ranging from approximately 62% to approximately 68% of maximum packing on 68 to 56 wt % D(2)SO(4), respectively. D(2)O evaporation from 68 wt % acid remains unaltered by the hexyl film, where it is most porous, but is impeded by approximately 20% from 56 and 60 wt % acid. H --> D exchange experiments further indicate that the hexyl film on 68 wt % acid enhances conversion of HCl and HBr into DCl and DBr, which is interpreted as an increase in HCl and HBr entry into the bulk acid. For this permeable hexyl film, the hydroxyl groups of surface hexanol molecules may assist uptake by providing extra sites for HCl and HBr hydrogen bonding and dissociation. In contrast, HCl --> DCl exchange in 60 wt % D(2)SO(4) at first rises with hexyl surface coverage but then drops back to the bare acid value as the hexyl species pack more tightly. HCl entry is actually diminished by the hexyl film on 56 wt % acid, where the film is most compact. These experiments reveal a transition from a porous hexanol film on 68 wt % sulfuric acid that enhances HCl and HBr uptake to one on 56 wt % acid that slightly impedes HCl and D(2)O transport.

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“…Overall, these data display the same general temperature dependence. In Figure we also included diffusion data from quasi-elastic neutron scattering. − Using this technique, c = 3.2 and 5 M aqueous H 2 SO 4 solutions (corresponding to n ≈ 14 and n ≈ 8, respectively) and a 6.1 M aqueous HNO 3 solution (corresponding to n ≈ 7) were investigated . At lower temperatures, the neutron data recorded for these more highly diluted acid hydrates indicate a somewhat faster diffusion than we observe via NMR.…”

Section: Results and Analysesmentioning

confidence: 99%

“…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. − …”

Section: Introductionmentioning

confidence: 99%

Dynamics in Glass Forming Sulfuric and Nitric Acid Hydrates

et al. 2013

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Deuteron nuclear magnetic resonance (NMR) and dielectric spectroscopy are utilized to investigate the dynamics in sulfuric acid hydrates as well as in nitric acid hydrates for various degrees of hydration. Near the glass transition temperature the electrical response is up to four decades faster than the calorimetric one, a feature found also for several other inorganic ionic liquids. The acid hydrates display pronounced super-Arrhenius behavior with fragility indices of the order of 100. The relaxation strength of the acid hydrates increases with increasing temperature, an observation that was rationalized with reference to the degree of molecular dissociation. Spin relaxometry and stimulated-echo spectroscopy revealed an overall isotropic reorientation process featuring a jump angle of about 30°. Finally, the implications of the present results for the understanding of the glass transition of pure ultraviscous water are discussed.

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Diffusion Coefficients in Cold Sulfuric Acid Solution

Cited by 9 publications

References 10 publications

Evaporation of Water through Butanol Films at the Surface of Supercooled Sulfuric Acid

Evaporation of Water through Butanol Films at the Surface of Supercooled Sulfuric Acid

Evaporation of Water and Uptake of HCl and HBr through Hexanol Films at the Surface of Supercooled Sulfuric Acid

Dynamics in Glass Forming Sulfuric and Nitric Acid Hydrates

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