Ionic-strength principle

They formulated the ionic-strength principle according to which in dilute solutions, the activity coefficient of a given strong electrolyte is the same in all solutions of the same ionic strength. ... 

The effect of added salts on the rate constant of a given ionic reaction has been studied for many years. The Br nsted-Bjerrum treatment of these salt effects has been particularly successful, the rate constant being related to the ionic strength of the solution. The observed trends can be quantitatively accounted for using the DHLL or a related expression for the activity coefficients of reactants and transition state. This subject has been reviewed in detail (Perlmutter-Hayman, 1971). The ionic-strength principle appears satisfactory when the reaction involves ions of opposite charge but less so when it involves ions of the same charge. 

To examine the validity of the ionic strength principle using measurements of solubility. 

Equation (12-29) provides a confirmation of Lewis ionic-strength principle. (More details concerning the thermodynamic treatment of electrolyte solutions can be found in Falkenhagen, Electrolyte, S. Hirzel Verlag, Leipzig, 1953, and H. S. Hamed and B. B. Owen, The Physical Chemistry of Electrolytic Solutions, Reinhold Publishing Corporation, New York, 1958.)... 

The Effect of Ionic Strength on an Equilibrium Constant (A Class Study). In J. A. Bell, ed. Chemical Principles in Practice. Addison-Wesley Reading, MA, 1967. 

Capillary Electrophoresis. Capillary electrophoresis (ce) is an analytical technique that can achieve rapid high resolution separation of water-soluble components present in small sample volumes. The separations are generally based on the principle of electrically driven ions in solution. Selectivity can be varied by the alteration of pH, ionic strength, electrolyte composition, or by incorporation of additives. Typical examples of additives include organic solvents, surfactants (qv), and complexation agents (see Chelating agents). 

Use of the K p for precipitation information is often complicated by a number of interfering factors including complexation of metallic ions, high ionic strength solutions, and high solids contents. This principle is applicable solely to ionic compounds, i.e., primarily inorganic compounds. 

Any factor that affects the size or shape of a molecule, the hindered movement of a fluorophore within a molecule, or the energy transfer within the molecule will affect the measured depolarization of its fluorescence emission. Therefore, the conformation of humic fractions in solution can be studied as a function of pH, ionic strength, temperature, and other factors by depolarization measurements. The principle of the method is that excitation of fluorescent samples with polarized light stimulates... 

The field of chemical oceanography/marine chemistry considers many processes and concepts that are not normally included in a traditional chemical curriculum. While this fact makes the application of chemistry to the study of the oceans difficult, it does not mean that fundamental chemical principles cannot be applied. The chapters included in this book provide examples of important chemical oceanographic processes, all taking place within the basic framework of fundamental chemistry. There are three principal concepts that establish many of the chemical distributions and processes and make the ocean a unique place to practice the art of chemistry (1) the high ionic strength of seawater, (2) the presence of a complex mixture of organic compounds, and (3) the sheer size of the oceans. 

The tendency of proteins to adsorb at interfaces is determined by many variables, including the pH, the ionic strength, the properties of the protein molecules and the interfaces, and the nature of the solvent and other components present. The process of protein adsorption is complicated, and despite the great volume of work over the past decades, a unified theory is still far ahead. Yet, some principles may be indicated. 

The behavior of practically all luminescent materials is sensitive to various parameters of physical and chemical origin. The excited state lifetimes and average intensities of the fluorescence and/or phosphorescence of these materials are modulated, for example, by temperature, oxygen, pH, carbon dioxide, voltage, pressure, and ionic strength. Consequently, the luminescence of various materials could be used, in principle, to monitor parameters of interest in medicine, industry, research, and the environment. 

While nature uses coenzyme-dependent enzymes to influence the inherent reactivity of the coenzyme, in principle, any chemical microenvironment could modulate the chemical properties of coenzymes to achieve novel functional properties. In some cases even simple changes in solvent, pH, and ionic strength can alter the coenzyme reactivity. Early attempts to present coenzymes with a more complex chemical environment focused on incorporating coenzymes into small molecule scaffolds or synthetic host molecules such as cyclophanes and cyclo-dextrins [1,2]. While some notable successes have been reported, these strategies have been less successful for constructing more complex coenzyme microenvironments and have suffered from difficulties in readily manipulating the structure of the coenzyme microenvironment. 

Images obtained by cryo electron microscopy should in principle be able to distinguish between the structural features proposed by the different models mentioned above [16]. The micrographs show a zig-zag motif at lower salt concentrations and they indicate that the chromatin fiber becomes more and more compact when the ionic strength is raised towards the physiological value (i.e., about 150 mM monovalent ions). 

In principle, the expressions for pair potentials, osmotic pressure and second virial coefficients could be used as input parameters in computer simulations. The objective of performing such simulations is to clarify physical mechanisms and to provide a deeper insight into phenomena of interest, especially under those conditions where structural or thermodynamic parameters of the studied system cannot be accessed easily by experiment. The nature of the intermolecular forces responsible for protein self-assembly and phase behaviour under variation of solution conditions, including temperature, pH and ionic strength, has been explored using this kind of modelling approach (Dickinson and Krishna, 2001 Rosch and Errington, 2007 Blanch et al., 2002). 

Another way to interpret the above observations would be in terms of the general principle that effective steric stabilization of polymer-coated droplets requires that the continuous phase be a good quality solvent for the polymeric stabilizer. Under poor quality solvent conditions (asi-casein at high ionic strength), the required entropic stabilizing repulsion of the adsorbed protein layer is converted into a destabilizing polymer-mediated attraction (Dickinson and Stainsby, 1982 Dickinson, 2006). 

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