Thermodynamic study of the mixed system (CsCl+CaCl2+H2O) by EMF Measurements at T=298.15K

In this paper, the cell potential method is used to determine the average activity coefficients of the NaBr–Na2SO4–H2O ternary system at 318.15 K. The ion-selective electrode and electrolyte solution are used to form a liquid-free battery. The ionic strength in the mixed solution is in the range 0.01–1.0 mol·kg–1 with different ionic strength fractions of Na2SO4, that is, y b = (0, 0.2, 0.4, 0.6, and 0.8). First, in a single salt solution, the response curve of Nernst can be obtained according to the Nernst equation. The standard cell potential E 0 = 251.03, electrode response slope k = 27.124, and linear correlation coefficient R 2 = 0.9998 are obtained in this work. In the same way, the average activity coefficients of NaBr in mixed electrolyte solution at 318.15 K were also determined by using the Nernst equation. Finally, the mixed ion interaction parameters θBr, SO4 and φNa, Br, SO4 of Pitzer equations can be fitted by the multilinear regression method combined with the average activity coefficients of mixed salt solution. In addition, the osmotic coefficients, water activity, excess Gibbs free energy, and activity coefficient of Na2SO4 can also be calculated using Pitzer equations based on the fitted θBr, SO4 and φNa, Br, SO4.

Section: Introductionmentioning

confidence: 99%

Average Activity Coefficients of NaBr in the Ternary System NaBr–Na₂SO₄–H₂O Determined by the Cell Potential Method at 318.15 K

Song

Sang

et al. 2021

“…In order to measure the thermodynamic properties of a mixed electrolyte solution, the most commonly used methods include equal pressure method, cell potential method, solubility method, etc. Compared with other methods, the cell potential method has the advantages of good selectivity, fast response, and easy continuous measurement. − …”

Section: Introductionmentioning

confidence: 99%

Mean Ionic Activity Coefficients of NaBr in the Ternary System NaBr–SrBr₂–H₂O at 288.15 K using the Cell Potential Method

Xing

Zhao

Sang³

et al. 2020

In this paper, a sodium ion selective electrode (Na-ISE) and a bromide ion selective electrode (Br-ISE) were used to form a liquid-free potential reversible battery: Na-ISE|NaBr (m 1 ) and SrBr 2 (m 2 )|Br-ISE. The mean ionic activity coefficients of NaBr in the ternary system NaBr− SrBr 2 −H 2 O at 288.15 K were determined using the cell potential method. In this system, the total ionic strength, I, ranges from 0.0100 up to 2.0000 mol • kg −1 for different ionic strength fractions y b of SrBr 2 , that is, y b = (0.0, 0.2, 0.4, 0.6, and 0.8). The results show that Na-ISE and Br-ISE have a great Nernst effect. The mean ionic activity coefficients of NaBr in NaBr− SrBr 2 −H 2 O were calculated using the Nernst equation, and the cell potential values were measured. The Pitzer ion interaction parameters θ Na + • Sr 2+ and ψ Na + • Sr 2+ • Br − were fitted using the Pitzer model, and experimental results in this work, and the mean ionic activity coefficients of SrBr 2 at 288.15 K were also calculated according to the Pitzer model. Finally, the osmotic coefficient Φ, water activity a w , and excess Gibbs energy G E of the ternary system were also calculated.

“…In recent years, it has been reported that most activity coefficients are determined at 298.15 K. For example, Hu et al reported the thermodynamic study of the mixed system (CsCl + CaCl 2 + H 2 O) by EMF measurements at T = 298.15 K. Pournaghdy et al finished the thermodynamic investigation of the ternary mixed electrolyte (CoCl 2 + CoSO 4 + H 2 O) system by EMF measurements at T = 298.15 K. Ghalami et al reported the thermodynamic study of the ternary mixed electrolyte (NaCl + NiCl 2 + H 2 O) system: application of the Pitzer model with higher-order electrostatic effects. Furthermore, our research groups have also investigated the mean coefficients of the mixed systems: for example, the mean activity coefficients of NaCl in the NaCl + CdCl 2 + H 2 O system, NaBr in the NaBr + SrBr 2 + H 2 O system, NaCl in the NaCl + SrCl 2 + H 2 O system, NaBr in the NaBr + Na 2 SO 4 + H 2 O system, NaBr in the NaBr + Na 2 B 4 O 7 + H 2 O system, and NaCl in the NaCl + CuCl 2 + H 2 O system at 298.15 K. − …”

Section: Introductionmentioning

confidence: 99%

Mean Activity Coefficients of NaCl in the NaCl + SrCl₂ + H₂O Ternary System at 278.15 K by the Cell Potential Method

Liu

Sang

et al. 2019

In this article, research on the thermodynamic mean activity coefficients for the ternary system (NaCl–SrCl2–H2O) has been carried out. A cell without a liquid junction can be expressed as sodium–ISE|sodium chloride (m A), strontium chloride (m B)|chlorine–ISE. It is used to determine the activity coefficients in these mixtures at 278.15 K by the cell potential method. Then, the total ionic strengths are I = 0.0100–3.0000 mol·kg–1 with different y b (ionic strength fraction) = (0.0, 0.2, 0.4, 0.6, and 0.8). The relationship diagrams between γ±NaCl (mean activity coefficients of NaCl) and y b (ionic strength fraction) were plotted. Mixed interaction parameters θNa,Sr and ψNa,Sr,Cl of this system in Pitzer equations at 278.15 K were fitted by using the determined activity coefficients and multiple regression method. In addition, those obtained parameters were also used to calculate γ±SrCl2 (mean activity coefficients of SrCl2) by the Pitzer equations. Accordingly, the osmotic coefficients, water activity, and excess Gibbs free energy in the mixtures were studied in detail.