Neutral salts, chemical potential

For diffusion in liquid electrolytes such as molten salts, two forces acting on an ion of interest should be taken into account the gradient of the chemical potential and the charge neutrality. Thus the electrochemical potential rather than the chemical potential should be the driving force for diffusion. 

Equation (6.148) is the well-known Donnan equilibrium of salt across a membrane in the presence of a polyelectrolyte, to which the membrane is permeable. It demonstrates the characteristic properties of the chemical potentials of neutral salts. 

Donnan dialysis is a membrane separation process that uses ion-selective membranes to prevent the flow of certain ions from one solution to another. A schematic of the process is presented in Figure 29.8. When a salt solution is separated from its corresponding acid by a cation-exchange membrane, the anions are excluded from the membrane, whUe the cations are redistributed across the membrane to attain Donnan equilibrium. By changing the salt solution periodically, it would be possible to shift the equilibrium favorably to effect simultaneous neutralization of acid on one side of the membrane (feed compartment) and acid recovery on the other side (receiver compartment). The driving force for ion migration is the chemical potential gradient for the cation across the membranes. 

The flux of electrolytes through ion exchange membranes based on a difference of chemical potential is low, except for the fluxes of acids and alkalis, compared with the flux in the presence of an electrochemical potential gradient. Therefore, to separate neutral salts by diffusion dialysis is economically limited, except for special cases. 

It is possible to measure the chemical potentials for salts, but not for the individual ions that compose them because electroneutrality must be maintained. So when you are dealing with simple systems, for example systems in which salts are distributed uniformly throughout a macroscopic volume, you can work with the chemical potentials of neutral molecules such as NaCl. In contrast, w hen you are interested in microscopic nonuniformities, such as the counterion distribution near a DNA molecule, or the electrostatic potential microscopically close to an electrode surface, then you can use the electrochemical potential. Charge neutrality need not hold in a microscopic region of... 

What is the chemical potential of a neutral salt that ionizes in solution For salts such as NaCl, add the electrochemical potentials of the separate ions to get the chemical potential of the neutral salt. For NaCl ... 

For a neutral salt the electrical term is canceled in the sum of anions and cations, and one obtains the chemical potential of the salt. Distribution of a neutral salt between two different solvents only requires that at equilibrium the ehemical potentials become equal, although eleetrie potential differenees may exist at the inlerfaee. 

We have assumed that the sample solution has been dialysed against a solvent v/hich contains a neutral salt of 1-1 type having a common counter-ion with the polyelectrolyte solution until the Donnan membrane equilibrium is attained. Moreover, we have also assumed that the diffusion coefficient of the polyion is so small that the chemical potentials of the simple ions are always equal throughout the entire solution at every moment during the diffusion process. That is, the diffusion process proceeds under conditions such that the Donnan equilibrium condition between the polymer phase and the solvent phase is always maintained. Then,... 

Cations (61),129 (62),130 and (63)131 were obtained as perchlorate or BF4- salts. The cations were characterized by NMR and X-ray methods reduction potentials and pXR+ values were also determined. Density functional calculations were performed on the tropylium derivative (64), a number of substituted analogues, and a number of neutral systems.132 The objective was to assess the utility of NICS (nuclear independent chemical shift) as a probe for detecting/sensing variation in aromaticity due to transannular tx-tt interactions. A dicyanoheptafulvene has been prepared, with X-ray crystallographic analysis showing a significant contribution from the dipolar resonance contributor (65).133 Addition of acid results in the tropylium... 

Be aware that every treatment from a dentist will involve chemical substances. If you have negative side effects from the treatment, take tri-salts to neutralize the reaction (see entry 302). Consider seeing a holistic dentist, as this may increase your chances of finding a practice without perfume and the like. See the dentist referral list of MCS America http //mcs-america.org/dentistlist.pdf. Be aware that not all the dentists on this list are familiar with MCS. Make sure you first talk with your potential new dentist about MCS and to see if he or she understands and respects your situation and can further help you. 

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