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The Effect of Deuteron Substitution in Wated on the Speed of Sound in Aqueus Solutions of 1-Propanol

Marczak W., Spurek M.

Molecular and Quantum Acoustics

2001

Vol. 22

157-163

Aqueous solutions of 1-alkans are often regarded as model systems in the investigation of hydration phenomena. The deuteron substitution in water changes the properties of aqueous alkans solutions as well as thode of such more complicated systems: cells, tissues and organs of living organisms. In this work, the speed of sound in mixtures of 1-propanol with D2O was compared with the speeds in binary solutions of methanol, ethanol and 1-propanol in H2O. A somewhat more pronounced hydrophobic hydration in D2O than in H2O is manifested by an effect similar to that resulting from the elongation of the alcohol molecule.

Transient cavities in liquids and the nature of the hydrophobic effect

Pohorille A.

Polish Journal of Chemistry

1998

Vol. 72, nr 7S

1680-1690

The size distributions of transient cavities in water and organic liquids, obtained from computer simulation, have provided a new means to analyze the nature of the hydrophobic effect and to evaluate the adequacy of different analytical models of this effect. The poor solubility of non-polar solutes in water is attributed to a low probability of finding in water cavities of atomic and molecular size. It has been shown that water applies more force per unit area of cavity surface than do hydrocarbon liquids. Models that successfully capture the main characteristics of the hydrophobic effect must at least include information about the density and the radial distribution of oxygen atoms in liquid water. One such model, quantitatively accurate for molecular solutes of arbitrary shape, is presented.

Effects of hydrophobic and hydrophilic hydration on the compressibility, volume and viscosity of mixtures of water with ß-picoline

Marczak W., Ernst S.

Bulletin of the Polish Academy of Sciences. Chemistry

1998

Vol. 46, No. 4

375-395

The speed of ultrasound in and the density of mixtures of water with ,ß-picoline were measured in the whole concentration range and within the temperature limits 293 = 298 K. The viscosities of those mixtures were measured at 293 K. The molar compressibility, molar volume and the corresponding excess and partial functions as well as the coefficients of the adiabatic compressibility and the excess activation energy of viscous flow were calculated. The results were discussed in terms of hydrophobic and hydrophilic molecular interactions. The hydrophobic hydration becomes evident in the thermodynamic properties of dilute aqueous solutions in that most probably labile semiclathrate structures, resembling cubic II solid clathrates (symmetry group Fd3m) but with guest molecules hydrogenbonded to the water host lattice, arise. With increasing concentration of the organic component the shortage of water leads to a gradual decay of the water polyhedra around the picoline molecules and hydrophilic hydration becomes predominant.