Relation between the characteristic molecular volume and hydrophobicity of nonpolar molecules

An approach is suggested to describe the solvophobic effects in various solvents, qualitatively and quantitatively. We analyzed the relationships between the Gibbs energies and enthalpies of solvation of alkanes in various solvents on the basis of existing experimental data. It is shown that for a large group of solvents, there is a linear correlation between the two quantities. Other solvents, primarily self-associated, show deviations from this line. These deviations are always positive, leading to a decrease in solubility, and can be used as a measure of the strength of the solvophobic effects. It is also shown that the solvophobic effects is not the only factor determining the solubility, even for alkane solutes. The magnitudes of contributions of the solvophobic effect into the Gibbs energies of solvation of various compounds in monohydric alcohols are determined. These magnitudes are found to be linearly correlated with a characteristic molecular volume of a solute. The slope of correlation grows up with the concentration of hydrogen bonds in the liquid solvent.

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“…A similar correlation for the hydrophobic effect in aqueous solutions has been found earlier:

\begin{matrix} left \\ Δ_{h.e.} G^{A} = 22.0 V_{x}^{A} + 3.65, \\ n = 58, σ = 1 .0 {9 kJ mol}^{- 1}, R^{2} = 0. 9847 \end{matrix}

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Section: Resultssupporting

confidence: 85%

Solvophobic effects and relationships between the Gibbs energy and enthalpy for the solvation process

Sedov

Stolov

2011

J of Physical Organic Chem

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“…An increased oxidation or functionalization of surface-bound species is known to support water uptake and facilitate nucleation ,,,, and may play a role here in lowering S ice for the highest OC/TC ratio (CAST-3, Figure ). On the other hand, while PAH are known to exhibit an overall negligible solubility in water, variations with the PAH molar volumes are observed. For instance, small PAHs and alkyl-PAHs such as those found on CAST-1 are shown to exhibit higher solubility than larger and unbranched PAHs, and thus surface species on CAST-1 may be more hygroscopic than those of CAST-3 at moderate temperatures (MPC regime), even though such property may not be as relevant for nucleation mechanisms involving vapor deposition.…”

Section: Resultsmentioning

confidence: 99%

Ice Nucleation Activities of Carbon-Bearing Materials in Deposition Mode: From Graphite to Airplane Soot Surrogates

et al. 2019

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Soot particles emitted by aircraft engines may act as ice nuclei (IN) within the atmosphere, subsequently triggering the formation of condensation trails. Such contrails might further evolve as cirrus clouds, and thus greatly influence the Earth's radiative budget and impact the amount of precipitation. In order to monitor in-situ deliquescence, efflorescence, and nucleation processes followed by ice growth in the laboratory, we developed the Ice and Droplet Nucleation Experimental Setup (IDroNES), which combines optical imaging and micro-Raman measurements to follow nucleation events in a pressure-, temperature-and humidity-controlled optical chamber. We first compare against literature data, and later confirm, the deliquescence relative humidities of micron-sized sodium chloride salt crystals in the -5°C to -35°C temperature range. Then, we investigate the ice nucleation activity of graphite and aircraft soot analogs, in the -15°C to -45°C temperature range, when exposed to humid nitrogen (N2/H2O gas flow). Soot samples exhibiting various surface chemistries, morphologies, and sizes are thoroughly examined via mass spectrometry, and spectroscopic and optical techniques. All carbon-bearing samples are found active at nucleating ice at low ice saturation ratios (Sice determined when the first crystal is detected). When normalizing Sice to the total surface area of a sample, one can derive the ice-active surface site density (ns). This parameter provides a means to compare the ice nucleating behavior of various particle types with distinct surface areas. As all samples studied in our work feature large surface areas, we provide ice nucleation data (Sice and ns) for a range of surface areas that remained largely unexplored to date. We find that the interplay between surface composition and morphology (micro, meso, and macro pores, surface roughness) influences the ice onset relative humidity.

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“…The last term, Δ int(sp) G A/H 2 O , equals zero if solute A does not form hydrogen bonds with water and can be neglected if only a small fraction of molecules are involved in H complexation. For such compounds, we have shown 11 that there is a correlation between Δ h.e. G A and V x A , the characteristic molecular volume 12 of A:…”

Section: ' Methodologymentioning

confidence: 95%

Determining the Gibbs Energies of Hydrogen-Bonding Interactions of Proton-Accepting Solutes in Aqueous Solutions from Thermodynamic Data at 298 K with Regard to the Hydrophobic Effect

Sedov

Solomonov

2011

J. Chem. Eng. Data

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Reaction rate and equilibrium constants in aqueous solutions are affected by the strength of hydrogen bonds formed between dissolved species and water molecules. Thermodynamic functions of hydrogen bonding with bulk water cannot be measured directly using spectroscopic methods, but the contribution of hydrogen-bonding processes to the thermodynamic functions of hydration may be determined using some model of aqueous solutions. We determined the Gibbs energies of hydrogenbonding interactions in water for various simple proton-accepting organic molecules on the basis of two different models that allow the contributions of nonspecific van der Waals interactions and the hydrophobic effect to be quantified. It is shown that hydrogen bonding with bulk water may be stronger than with a single water molecule. The influence of solute structure on the Gibbs energy of hydrogen-bonding interactions is discussed.

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Relation between the characteristic molecular volume and hydrophobicity of nonpolar molecules

Cited by 14 publications

References 21 publications

Solvophobic effects and relationships between the Gibbs energy and enthalpy for the solvation process

Solvophobic effects and relationships between the Gibbs energy and enthalpy for the solvation process

Ice Nucleation Activities of Carbon-Bearing Materials in Deposition Mode: From Graphite to Airplane Soot Surrogates

Determining the Gibbs Energies of Hydrogen-Bonding Interactions of Proton-Accepting Solutes in Aqueous Solutions from Thermodynamic Data at 298 K with Regard to the Hydrophobic Effect

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