Mean activity coefficient of sodium sulfate in aqueous sodium sulfate-sodium chloride electrolytes

Abstract

tetrachloride did not remain constant after initial calibration but decreased rapidly toward zero. For example using a 0.1 M sample of DMF in carbon tetrachloride, the AT reading 2 min after the sample drop was placed on the thermistor was 5.20,l min later it was 3.20, and after 15 min AT was 0.03. The rate of AT decrease for DRlA solutions was slightly lower. This behavior would be expected with solutes whose vapor pressures were too high for study by this method and would lead to spuriously high molecular weights.The activity coefficient of NazSOc in aqueous NazS04-h'aC1 electrolytes at 25" and total ionic strength 1.0 has been measured using the cell Pb(Hg)IPbSOl(s)/Na+, S04*-, C1-, HzO/glass electrode where the glass electrode is reversible to Na+. If care is taken to exclude oxygen from the cell during preparation and measurements, reproducibility of the order of &0.05 mV is obtained. Harned's rule was found to be obeyed within experimental error for Na2S04 (component 2) in these mixtures, and the coefficient aZl at I = 1 was calculated by a least-squares method to be -0.035 i 0.005. This agrees with the value of azl calculated from published osmotic coefficients and activity coefficients of NaCl (component 1) in the corresponding mixtures.

Vapor Pressure and Dissolution Enthalpy Measurements in Ternary {H2O + NaCl + Na2SO4} System between 298 K and 363 K

“…The performances of two models are compared in Table 6 in which mean relative deviations between calculated values and experimental ones taken from literature are reported. Results obtained with Pitzer are satisfactorily excepting in the case of Synott et al 12 data. It is evident that electrolyte-NRTL represents the data with a less good accuracy.…”

“…Though numerous experimental and theoretical investigations have been reported on binaries {NaCl + H 2 O} (see for example, Clarke and Glew 6 ) and {Na 2 SO4 + H 2 O} (see, for example, Marliacy et al 7 and references therein), much less data exists on the {NaCl + Na 2 SO 4 + H 2 O} ternaries. Thus, Tischenko et al 8 made measurements of mean activity coefficients of NaCl and Na 2 SO 4 in water at various composition between 278 and 318 K. However, most VLE data on this system were reported at 298 K; the reports concern the determination of osmotic coefficients by isopiestic methods (Robinson et al, 9 Platford, 10 and Wu et al 11 ) or the direct measurements of activity coefficients from electrochemical techniques (Synott and Buttler 12 and Lanier 13 ). Similarly, calorimetric data of aqueous {Na 2 SO 4 + NaCl} are very scarce; heats of mixing measurements of sodium sulfate and sodium chloride solutions were reported by Snra and Wood 14 at ambient temperature, and more recently, Conti et al 15 measured isobaric heat capacities for aqueous solutions containing the system Na-K-Cl-SO4 from 333 K to 473 K.…”

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

“…From the experimental potential differences (AE), the activity coefficient of NaCl was calculated, according to Equation 1, and then corrected to a round value of ionic strength as described previously (4). Both the corrected and uncorrected values are given in Table I.…”

Determination of gold in natural waters at the parts per billion level by chelation and atomic absorption spectrometry

“…This selectivity and thermodynamic reversibility is well documented in dilute solution (7), as well as in concentrated solutions containing a single salt component (2). Relatively concentrated multicomponent solutions have been studied by means of cells such as (3,4) Ag/AgCl/Na+, Cl-, Jf/glass electrode where X is a cation or anion which does not interfere with the operation of either the Ag/AgCl or glass electrode. Such data have been verified (for X -Mg2+, Ca2+, and S042-) by measurements with amalgam electrode cells such as (5)(6)(7) Ag/AgCl/Na+, Cl-, A7Na(Hg)…”