Dielectric constant of solution

With this simple background model, then, it is easy to see that there will be a decrease of the dielectric constant of solutions (compared with that of the original... 

Studies of the dielectric constant of solutions and the relaxation times of water in the presence of ions have been refined since the 1980 s and indeed difficulties do turn up if one looks at data from measurements over large frequency ranges. The variation of the dielectric constant with frequency has been studied particularly by Winsor and Cole, who used the Fourier transform of time domain reflectometry to obtain dielectric constants of aqueous solutions and the relaxation times in them. Their frequency ranges from over 50 MHz to 9 GHz. 

Measurements of dielectric constants of solutions allow the deduction of not only how many waters are taken up and held irrotationally by ions, but also how the ions affect the frequency of the movements of molecules near them. This will help a person interested in electrostatic effects calculate the local pressure near an ion (Section 2.22.1). 

In most of the modem versions of the Debye-Hiickel theory of 1923, it is still assumed that the dielectric constant to be used is that of water. The dielectric constant of solutions decreases linearly with an increase in the concentration of the electrolyte. Using data in the chapter, calculate the mean activity coefficient for NaCl from 0.1 M to 2 M solutions, using the full equation with correction for the space taken up by the ions and the water removed by hydration. Compare the new calculation with those of Stokes and Robinson. Discuss the change in a you had to assume. 

Dipole Moments and Dielectric Increments of Amino Acids, Peptides and Proteins. Dielectric constants of solutions of amino acids, peptides and proteins always are higher than those of the pure solvent, even when the solvent is a liquid as polar as -water In dilute solution the dielectric constant, s, is a linear function of the solute concentration, c... 

Wyman, J. jr. The Dielectric Constant of Solutions of Dipolar Ions. Chem. 

Some of the facts that Hasted et al. established are shown in Table 2.11. They found that the lowering of the dielectric constant of 1 M solutions is in the range of 10-20%. This can be nicely explained by taking the water in contact with the ion as dielectrically saturated (unable to orient on the demand of the external field), but still having a dielectric constant of only 6, compared with the value of 80 for bulk water unaffected by ions. The table shows the number of water molecules per ion pair that one has to assume are saturated (i.e., irrotationally bound in the vicinity of each ion) to make the above model come out right (i.e., reproduce the measured dielectric constants of solutions). This model leads to a very simple equation for the dielectric constant of a solution ... 

It is unfortunately true, however, that electric moments of substances determined from measurements on the dielectric constants of solutions are not independent of the solvent used, as has been shown by Muller20 and others. Some typical values of the apparent electric moment, ft, of nitrobenzene in a series of solvents are given in Table III, from the work of Jenkins.21 For this case, at least, there is a tendency... 

By measuring the static dielectric constant of solutions of polar polymers in nonpolar solvents, one may calculate a statistical mean dipole of the macromolecule. With polar solvents interesting information can be obtained concerning the interaction between polymer and solvent molecules. Finally the study of relaxation phenomena, including the accurate determination of the critical frequencies may lead us to a better knowledge of the statistical unit and of its interaction with its environment. 

Perkyns and Pettitt [105] demonstrated that the ionic and dipolar routes to the dielectric constant of solution are consistent both with and without Debye screening, provided the screened correction is specified in the reciprocal space as... 

Dg - dielectric constant of solution containing molecular but no ionic... 

Effect of copolymer composition on degradation rates of biodegradable polymer nanofibers. Concluded that conductivity or dielectric constant of solution determined fiber morphology. 

AFC electrolyte a, on order of 1-100 S/m at operating temperature 0.5-2.0 mm Ion concentration, temperature, charge number on ion, dielectric constant of solution, mobility, viscosity, degree of ion dissociation, other liquids... 

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