Mean salt method

The mean salt method derives implicitly from the concept of ionic strength, as expressed by Lewis and Randall (1921). It is assumed that, within the range of the ionic strength of interest, for a standard uni-univalent electrolyte such as KCl, the following assumption is valid ... 

Figure 8JO Comparison between individual ionic activity coefficients obtained with Debye-Hiickel equation and with mean salt method for various ionic strength values. Reprinted from Garrels and Christ (1965), with kind permission from Jones and Bartlett Publishers Inc., copyright 1990.

Example 3.1 Determination of single-ion activity coefficients for Ca from mean values for CaCl2 using the mean-salt method. 

In the mean-salt method, the behavior of KCl in solution is the standard basis for obtaining individual ion activity coefficients. Various lines of evidence indicate that /k+ and fc - have similar values that is, as an approximation,... 

Single-ion activity coefficients at higher ionic strength are estimated by using an empirical approach in which complex ion and dipole interactions are accounted for by direct laboratory measurements. One such experimentally based approach that can be applied to seawater is the mean salt method (MSM). This procedure is based upon measurements... 

This assumption seemed reasonable in view of the similarity of the sizes and limiting conductances of the two ions. It gave rise to the Macinnes convention, which enables the activity coefficients of other ionic species to be evaluated from the known mean activity coefficients of selected electrolytes. This process, called the mean salt method", has been used extensively and with apparent success in studies of the seawater medium. Carrels and Thompson (40,41) used a glass electrode reversible to Na" to establish a reference point for the activity coefficient of that ion in seawater. The Macinnes convention was then applied to obtain data for the other ions present. The procedure proposed by Maronny and Valensi (42,43) for the determination of standard pH values utilizes Equation 6, where is... 

Similarly, the same method and the same mean salt furnish values of individual ionic activity coefficients for other ions—e.g., the sulfate group SO " ... 

Another arylation method, in the case of nitrogen heterocycles, does not need a halogenated derivative but a heterocycle activated by triflic anhydride260,261 (reaction 22). Simple aryl halides usually do not react with phosphines and special methods therefore have to be used for their arylation. The most widely used is the complex salt method , in which an aryl halide is heated with a phosphine in the presence of a transition metal such as nickel (II)2e (reaction 23). The catalytic cycle probably takes place by means of a reduced nickel(I) complex, generated in situ from the starting nickel(II) salt this nickel(I) species could undergo an oxidative addition of the aryl halide to yield a transient nickel(III) adduct, which after the reductive elimination of the aryphosphonium affords the recovery of the first active-nickel(I) complex (reaction 24). 

In order to inquire further into the ideality of molten mixtures investigated by this or any other means, the method of expressing mole fractions must be considered. The problem can be realized by the following for a nominal 1 mole % concentration of Ag2S04 or PbCF in AgNOs solvent, should the solute be counted once, twice, or three times In fact, Ag2S04 in this case behaves as if N = 0.99, whereas with PbCU is close to 0.97. The reason for this is basic to the ionic constitution of molten salts. The... 

Initially, the only means of obtaining elements higher than uranium was by a-particle bombardment of uranium in the cyclotron, and it was by this means that the first, exceedingly minute amounts of neptunium and plutonium were obtained. The separation of these elements from other products and from uranium was difficult methods were devised involving co-precipitation of the minute amounts of their salts on a larger amount of a precipitate with a similar crystal structure (the carrier ). The properties were studied, using quantities of the order of 10 g in volumes of... 

Hydrolysis of a sulphonamide. Mix 2 g. of the sulphonamide with 3-5 ml. of 80 per cent, sulphuric acid in a test-tube and place a thermometer in the mixture. Heat the test-tube, with frequent stirring by means of the thermometer, at 155-165° until the solid passes into solution (2-5 minutes). Allow the acid solution to cool and pour it into 25-30 ml. of water. Render the resulting solution alkaline with 20 per cent, sodium hydroxide solution in order to liberate the free amine. Two methods may be used for isolating the base. If the amine is volatile in steam, distil the alkaline solution and collect about 20 ml. of distillate extract the amine with ether, dry the ethereal solution with anhydrous potassium carbonate and distil off the solvent. If the amine is not appreciably steam-volatile, extract it from the alkaline solution with ether. The sulphonic acid (as sodium salt) in the residual solution may be identified as detailed under 13. 

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

The cobalt catalyst can be introduced into the reactor in any convenient form, such as the hydrocarbon-soluble cobalt naphthenate [61789-51 -3] as it is converted in the reaction to dicobalt octacarbonyl [15226-74-17, Co2(CO)g, the precursor to cobalt hydrocarbonyl [16842-03-8] HCo(CO)4, the active catalyst species. Some of the methods used to recover cobalt values for reuse are (11) conversion to an inorganic salt soluble ia water conversion to an organic salt soluble ia water or an organic solvent treatment with aqueous acid or alkah to recover part or all of the HCo(CO)4 ia the aqueous phase and conversion to metallic cobalt by thermal or chemical means. 

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