Activity measurements in concentrated sodium chloride-potassium chloride electrolytes using cation-sensitive glass electrodes

Abstract

gold without interferences from samples containing as high as 100 ppm of complexed mercury. Cyanide solutions also interfere with the chelation procedure; however, this interference can be obviated by first oxidizing the solution with potassium permanganate-hydrochloric acid solution.The polyschiff base column provides an effective means of concentrating ionic and colloidal gold from natural water samples. The use of atomic absorption spectrometry, combined with the chelation procedures used here permits the detection limit of this method to be 0.5 ppb/liter of sample. It is possible to lower the detection limit to considerably smaller values by passing the appropriate amount of sample through the column. Because the concentration procedure and measurement of the gold are completely independent from each other, techniques other than atomic absorption spectrometry could be applied as a means of measurement. Such a procedure using a colorimetric end point is presently being investigated.

Quaternary System Thermodynamic Investigation in a Mixed Solvent: NaCl + KCl + N,N-Dimethylformamide + H2O

“…Figure indicates the relation between activity coefficients of sodium chloride γ ±NaCl and the ionic strength I for diverse percentages of DMF in water together with the pure water (zero percentage). For pure water, the results of this work are in satisfactory agreement with those by Butler and Huston, and for other percentages, the results presented in Figure show that activity coefficients of sodium chloride (except for pure water) reduced by an increase in the values of ionic strength; this fact may be attributed to the mutual ion–ion interactions. An inspection of Figure reveals that the activity coefficients of the studied systems decrease by increasing the percentages of DMF in the mixed solvent, and this may be ascribed to the electrostatic attraction between the ions as a result of the decreasing trend of the solvent dielectrics.…”

“…The estimated parameters, θ NaK and ψ NaKCl account for the short-range interactions between two ions of the same sign (anions) and two anions plus cations, which are important only at high ionic strengths. As can be seen in Table 5, these parameters agree well with the result in pure solvent from Butler and Huston, 38 and for all cases, the parameters for the ternary ion−ion−ion interaction are an order of magnitude less than the binary ion−ion parameters. It should be noted that with increasing percentage of solvent mixtures, we did not see a clear trend regarding these parameters.…”

Potentiometric studies of multicomponent activity coefficients using the lanthanum fluoride membrane electrode

“…If the ionic strength fraction of NaF, X2, is defined by °Errors are statistical 95 % confidence limits. 6 Glass compositions were NAS 11-18 aged 1 yr (C) or new (C') and LAS 10-23 (B).…”

Extended traceability of pH: an evaluation of the role of Pitzer's equations

“…The median is not different from the value ψ Na-K-Cl =-0.0098 given by KF -a consequence of the almost normal distributions of the binary coefficients and smoothing of the ternary data in Ref. [48]. A KolmogorovSmirnov test results in a probability of less than 1% that the CDF is normal, however.…”

“…These data are of interest because the extended MacInnes splitting convention is based on KCl. In addition, 30 NaCl activity coefficient data from Table 16 [37] are used to obtain CDF (cumulative distribution functions) for NaCl which were subsequently used in conjunction with 20 activity coefficients in the ternary system Na-K-Cl from [48] (electrode C data only) to obtain uncertainty estimates for ternary coefficients.…”