Effect second salt

Since much work has gone into eventually disproving this mechanism for hydrogen exchange it is worth examining the soundness of the experimental data upon which the theory was based. Firstly, the log rate coefficient versus acidity function plots should have had unit slopes and the fact that they did not was attributed to salt effects. Secondly, different rate coefficients were obtained at the... 

We can use Le Chatelier s principle as a guide. This principle tells us that, if we add a second salt or an acid that supplies one of the same ions—a common ion —to a saturated solution of a salt, then the equilibrium will tend to adjust by decreasing the concentration of the added ions (Fig. 11.15). That is, the solubility of the original salt is decreased, and it precipitates. We can conclude that the addition of excess OH- ions to the water supply should precipitate more of the heavy metal ions as their hydroxides. In other words, the addition of OH ions reduces the solubility of the heavy metal hydroxide. The decrease in solubility caused by the addition of a common ion is called the common-ion effect. 

Effect of salt type and concentration The ionic strength of the aqueous solution in eontaet with a reverse micelle phase affects protein partitioning in a number of ways [18,23]. The first is through modification of electrostatic interactions between the protein surface and the surfaetant head groups by modifieation of the eleetrieal double layers adjacent to both the eharged inner mieelle wall and the protein surface. The second effect is to salt out the protein from the mieelle phase because of the inereased propensity of the ionie speeies to migrate to the micelle water pool, reduee the size of the reverse mieelles, and thus displace the protein. 

Hofmeister, F. (1888). On the understanding of the effect of salts. Second report. On regularities in the precipitating effects of salts and their relationship to their physiological behavior. Naunyn-Schmiedebergs Arch. Exper. Path. Pharmakol. (Leipzig) 24 247-260. 

Salts also affect the equilibria between free ions and ion pairs. The most obvious action is the second salt effect (common ion effect), namely suppression of free ions ... 

Salts have a much greater influence on aliphatic amine initiated polymerizations. If the primary effect of salt was to influence the position of equilibria this difference might not have been expected. In the second case there is a significant concentration of betaine present for salt to coordinate to and activate by mechanism (ii). 

In many cases the soluSility of a substance is not changed very much by the addition of small amounts of other substances to the solution. Ordinarily, for example, the presence of a non-ionizing solute, such as sugar or iodine, has very little effect on the solubility of a salt in water, and conversely the presence of a salt such as sodium nitrate has little effect on the solubility of iodine or other nonionizing substances iii water. Also the presence of a salt which has no ion in common with another salt tvhose solubility is under consideration ordinarily produces only a rather small effect on the solubility of the second salt, usually a small increase. 

In many cases mixed electrolyte systems can he added to a latex either adventitiously or deliberately. Hieir effects on the stability of dispersions can best be summarized by Fig. 22. The axes of this figure are plotted as a percentage, so that the abscissa is the ccc value of salt 1 expressed as a percentage of its ccc value in the absence of the second salt salt 2 is expressed on a similar basis. Thus, the simplest possible case is additivity in... 

So far, we have discussed aqueous solutions containing a single, dissolved ionic salt, MX. Now we consider the effect of adding a second salt which has one of its ions in common with the hrst salt. 

If one accepts the continuum, linear response dielectric approximation for the solvent, then the Poisson equation of classical electrostatics provides an exact formalism for computing the electrostatic potential (r) produced by a molecular charge distribution p(r). The screening effects of salt can be added at this level via an approximate mean-field treatment, resulting in the so-called Poisson-Boltzmann (PB) equation [13]. In general, this is a second order non-linear partial differential equation, but its simpler linearized form is often used in biomolecular applications ... 

Some reaction rates depend on relative concentrations of H or OH . Then the addition of outside salts, lowering activities coefficients, facilitates the dissociation degrees of weak acids and bases, therefore the concentrations of their ions, in particular H or OH. Such effect is called second salt effect and is usually checked by the change in H+ content through equation... 

An increase in concentration Oion of added salt ions, leads to the penetration of salt ions into the star interior and a decrease in the differential osmotic pressure. When the concentration of added ions sufficiently exceeds the average concentration of counterions in the osmotic star, the polyion is found in the so-called salt-dominated regime. Here, the differential osmotic pressure of ions is equivalent to that created by binary monomer-monomer interactions with an effective second viral coefficient Ueff = a /24>ion. As a result, one recovers the same scaling dependence for the size of a PE star as that found for neutral star polymer under good solvent conditions, (4), with replacement u —> Uetr ... 

Under salt dominance conditions (i.e., when the concentration of salt, Oion, exceeds by the far the concentration of counterions in salt-free osmotic corona), the electrostatic interactions in the corona are described via an effective second... 

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