Transference numbers of sodium chloride in concentrated aqueous solutions and chloride conductances in several concentrated electrolyte solutions

Stable chlorine electrodes with low bias potentials have been developed by introducing 25% Ir+75% Pt electrodes and an improved gas line. With their use in cells with transference, cation constituent transference numbers have been measured at 25°C in NaCl solutions from 1.7 to 6 modal. These results agree well with four other sets of data in the literature but disagree with two further sets based on emf determinations with Ag/AgCl electrodes. A table of best NaCl transference numbers is proposed. The conductances of the chloride ion-constituent in concentrated NaCl, KCl, and HCl solutions are compared.     

The determination of hydroxide and carbonate in concentrated sodium chloride solutions

A computer method for the determination of carbonate and hydroxide in concentrated (2.89 M) sodium chloride solutions is described. The method is based on multiparametric curve-fitting and can also be applied to salts of dibasic acids with unknown equilibrium constants. The systematic error is not more than 1%. The titration and calculation takes less than 20 min.     

Mercury passivation solutions of potassium chloride and sodium hydroxide and hypochlorite

Formation of anodic films on the surface of mercury in solutions of potassium chloride and sodium hydroxide and hypochlorite and the effect of these films on mercury passivation were studied by the potentiostatic method.     

The ionic product of water in concentrated tetramethylammonium chloride solutions

The ionic product of water, pK(w) = - log[H(+)][OH(-)] has been determined in aqueous solutions of tetramethylammonium chloride over the concentration range of 0.1-5.5 M at 25 degrees C using high-precision glass electrode potentiometric titrations. pK(w) data relating to aqueous potassium and sodium chlorides at ionic strengths up to 5 M are markedly lower than the tetramethylammonium chloride results. These differences are almost certainly due to weak associations between potassium and (especially) sodium and hydroxide ions.     

Structure of concentrated aqueous solutions of scandium chloride

It is shown via X-ray diffraction that aqueous solutions of scandium chloride form ionic associates in a wide range of concentrations. It is established that the Sc³⁺ ion coordination number increases upon dilution to 8.2 at an unchanged Sc³⁺–OH² distance of 0.215 nm. The second coordination sphere of the cation forms at an average distance of 0.420 nm. The number of solvent molecules in the sphere logically increases during dilution. It is concluded that the anion does not form its own sphere in highly concentrated solutions. This coordination sphere begins to form only in solutions with moderate concentrations at a distance of 0.315 nm, and it contains six water molecules in diluted solutions.     

A potentiometric multisensor system for determining lysine in aqueous solutions containing potassium and sodium chloride

A potentiometric multisensor system has been developed for the determination of lysine in aqueous solutions containing sodium and potassium chlorides. The sensor array includes a cross-sensitive sensor, the response of which is the Donnan potential at the ion-exchange polymer/test solution interface, a set of ion-selective electrodes, and a silver-silver chloride reference electrode. Multidimensional regression analysis has been employed for the calculation of component concentrations. The relative error of determining lysine, potassium, and sodium did exceed 10% in the tested solutions.     

Electro-osmotic pumping of sodium chloride solutions

Electro-osmotic pumping (EOP) theory and its characteristics (transport numbers, brine concentration, current density, current efficiency, electro-osmotic coefficients, etc.) of Selemion AMV and CMV ion-exchange membranes were studied. The brine concentration increased with increase in current density and feed water concentration. Current efficiency was nearly constant in a wide range of current densities and feed water concentrations. The water flow through the membranes also increased with increasing current density and feed water concentration. The increase in water flow increased the current efficiency significantly. Consequently, water flow through electrodialysis (ED) membranes had a positive effect on ED. Electro-osmotic coefficients decreased with increasing feed water concentration. Osmotic flow in EOP-ED decreased relative to the total flow with increasing current density while the electro-osmotic flow increased relative to the osmotic flow. Osmotic flow significantly contributes to the total water flow in EOP. Selemion AMV and CMV membranes performed well for salt concentration. A simple membrane potential measurement has been demonstrated to function reasonably satisfactorily to predict membrane performance for salt concentration.     

Conductivity and electrochemical stability of concentrated aqueous choline chloride solutions

Russian Journal of Physical Chemistry A - The conductivity and electrochemical stability of choline chloride (ChCl) solutions with water contents ranging from 20 to 39 wt % are studied. Exposing...     

The thermodynamics of aqueous borate solutions I. Mixtures of boric acid with sodium or potassium borate and chloride

Potentials for the cell without liquid junction where M is sodium or potassium are reported over a range of ionic strength to I=3 mol-kg^–1 at 5 to 55°C. Total boron concentration in the solutions was restricted to low levels to minimize formation of polynuclear boron species. Cell potentials are treated with the Pitzer ion interaction treatment for mixed electrolytes, with linear ionic strength dependence assumed for the activity coefficient of undissociated boric acid. Trace activity coefficients of sodium and potassium borates in chloride media are calculated at various temperatures.     

The ionic product of water in highly concentrated sodium perchlorate solutions

The ionic product of water, pK(w)=-log[H(+)][OH(-)], has been determined in aqueous solutions of sodium perchlorate over the concentration range of 1.0-8.0 M at 25 degrees C from high-precision potentiometric titrations carried out in cells with liquid junction using both glass and hydrogen electrodes. The glass electrode results are systematically lower probably as a result of interference by Na(+) ions.     

Preparation of thorium concentrate from concentrated calcium chloride solutions

Extraction, washing, back extraction, and precipitation of Th(IV) from the backwash in the hydrochloric acid processing of perovskite are studied. Process conditions are optimized to obtain a concentrate with a ThO₂ content of about 85 wt %.     

Trace analysis in highly concentrated salt solutions of sodium chloride and ammonium fluoride using flame atomic absorption spectrometry

Summary Aqueous solutions of high salt concentration are subjected to direct flame atomic absorption analysis. Blockage of nebulizer and burner is eliminated by employing the dosage scheme washing solution — sample — washing solution effected by means of a specially designed device. The microtrace content of bismuth, zinc and copper in sodium chloride and of copper, lead and iron in ammonium fluoride is determined by the standard addition method. Matrix effects are reduced in the analysis of sodium chloride by the addition of ethanol and in the analysis of ammonium fluoride by pre-heating of sample and washing solution. In order to improve the signal-to-noise ratio, ensemble summation is applied.The following trace element concentrations are determined: 0.5 mg/kg of Cu; 5 mg/kg of Bi and 0.25 mg/kg of Zn in sodium chloride and 0.47 mg/kg of Cu; 0.1 mg/kg of Pb and 3.7 mg/kg of Fe in ammonium fluoride.

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Bestimmung von Spurenelementen in hochkonzentrierten Salzlösungen (NaCl, NH₄F) mittels Flammen-Atom-Absorptions-Analyse

     

Thermodynamics of aqueous mixtures of sodium chloride,potassium chloride,sodium sulfate,and potassium sulfate at 25°C

Aqueous solutions of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate can be mixed in six ways to give ternary mixtures. Two of these have already been studied and results are now presented for the remaining four systems: H₂O–NaCl–K₂SO₄, H₂O–Na₂SO₄–K₂SO₄, H₂O–KCl–Na₂SO₄, and H₂O–KCl–K₂SO₄.     

Dehydrochlorination of vinylidene chloride-vinyl chloride copolymer by aqueous sodium or potassium hydroxide solutions under two-phase conditions

The reaction of solid copolymer of vinylidene chloride and vinyl chloride with aqueous sodium or potassium hydroxide solutions in the presence of quaternary ammonium or phosphonium salts as phase transfer catalysts gave dehydrochlorinated products with chlorine-substituted polyene structure. Among the catalysts used tetrapropylammonium bromide was the best and potassium hydroxide was more active than sodium hydroxide. The activity of quaternary ammonium salts was discussed in terms of hydrophile–lipophile balance. The effects of temperature and the concentration of the bases and catalysts were investigated to obtain the optimum reaction condition. Treatment of the polymer films and solutions in tetrahydrofuran with aqueous bases under two-phase conditions also produced dehydrochlorinated films and powders.     

Amino acid hydration in aqueous ammoniu chloride and sodium chloride solutions

Partial volumes $\bar V^0$ of amino acids in aqueous NH₄Cl and NaCl solutions are discussed. The salts have different effects on water structure. The contributions of the charged NH ₃ ⁺ and COO^? groups of amino acids are found. Structural characteristics of hydrated complexes are calculated: partial volumes of water inside and outside the hydration sphere and hydration numbers. The same value of $\bar V^0$ (NH ₃ ⁺ , COO^?) is achieved at a higher NH₄Cl concentration. The two salt systems with the same $\bar V^0$ (NH ₃ ⁺ , COO^?) have similar values of the partial volumes of water and hydration numbers.     

Aggregation of sodium dodecyl sulfate in aqueous sodium chloride solutions

Summary Aqueous solutions of sodium dodecyl sulfate with added sodium chloride (0–0.3 mol kg^–1) were studied at 298.2 K in order to calculate the molar standard free energy of micelle formationG _m . The following properties were measured: (i) aggregation number by membrane osmometry, (ii) counter-ion binding and sodium ion activities by electromotive force, (iii) critical micelle concentration by electromotive force and fluorescence spectrophotometry. The results indicate thatG _m . is independent of the NaCl concentration.