The Maximum of Minimal Conductivity in Aqueous Electrolytes

2020 ◽  
Vol 234 (1) ◽  
pp. 1-10
Author(s):  
Volker Ender ◽  
Jens Weber
Keyword(s):  
Alkali Metal ◽  
Aqueous Solutions ◽  
Pure Water ◽  
Molar Conductivity ◽  
Alkali Metal Ions ◽  
Aqueous Electrolytes ◽  
Weak Base ◽  
Intrinsic Conductivity ◽  
Cesium Ions ◽  
Limiting Condition

AbstractThe present paper deals with the minima of conductivity in aqueous solutions, which occur due to the hydrolysis reaction with added bases. The minima show lower conductivities than the intrinsic conductivity of pure water. The minimum is a function of the molar conductivity of the added ions. There exists a limiting condition of <75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 for the occurrence of a minimum in the real (positive) concentration area. Values higher than 75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 lead to minimas in the virtual (negative) concentration area. Connecting all the minima, a curve with a maximum is observed. This point is given by 75.825 ⋅ 10−4 S ⋅ m2 ⋅ mol−1 and the intrinsic conductivity of pure water. The effect is independent of whether the added substances come from a strong or weak base. So far, the phenomenon should not influence measurements of conductivity under usual circumstances, but might be more of academic interest. Interestingly, we found that the effect for Rubidium and Cesium ions is different compared to other alkali metal ions. No minimum conductivity is predicted for these ions.

scholarly journals Mobility of hydrated alkali metal ions in metallosupramolecular ionic crystals

2019 ◽  
Vol 10 (2) ◽  
pp. 587-593 ◽  
Author(s):  
Nobuto Yoshinari ◽  
Satoshi Yamashita ◽  
Yosuke Fukuda ◽  
Yasuhiro Nakazawa ◽  
Takumi Konno
Keyword(s):  
Solid State ◽  
Alkali Metal ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Alkali Metal Ions ◽  
Ionic Crystals ◽  
Ionic Solids ◽  
Ion Conducting

The ion-conducting behaviour of alkali metal ions in ionic solids (M6[1]·nH2O) resembles that in aqueous solutions; the solid-state conductivities increase in the order of M = Li+ < Na+ < K+.

scholarly journals CONSTANTS OF ELECTROLYTIC DISSOCIATION OF THE LITHIUM, SODIUM AND POTASSIUM SULFATES IN AQUEOUS ISOPROPANOL SOLUTIONS

2020 ◽  
Vol 63 (3) ◽  
pp. 16-22
Author(s):  
Ivan M. Borisov ◽  
Azamdzhon A. Nabiev
Keyword(s):  
Alkali Metal ◽  
Aqueous Solutions ◽  
Dissociation Constant ◽  
Salt Concentration ◽  
Volume Content ◽  
Molar Conductivity ◽  
Electrolytic Dissociation ◽  
Weak Electrolytes ◽  
Sodium And Potassium ◽  
Aqueous Isopropanol

At introduction of isopropyl alcohol in saturated aqueous solutions of sulfates of lithium, sodium and potassium at 25 °C physico-chemical properties of the studied systems Li2SO4-H2O-C3H7OH, Na2SO4-H2O-C3H7OH and K2SO4-H2O-C3H7OH are changed. This reduces the density of solutions and salt content in aqueous isopropanol solutions due to a decrease in solubility of salts. It is shown that the variation of the volume content of alcohol from 0% to 90% results in the decrease of Li2SO4 solubility 1280 times, Na2SO4 – 548 times, K2SO4 – in 278 times. Alcohol additives also affect the degree of electrolytic dissociation of salt in aqueous isopropanol solutions. To study the electrochemical properties of salts we used conductometric method based on the measurement of the molar conductivity of solutions depending on salt concentration. In aqueous solutions, alkali metal sulfates exhibit the properties of strong electrolytes and almost completely dissociate into ions. When the volume content of isopropanol in the solution is more than 30%, alkali metal sulfates begin to show the properties of weak electrolytes, as evidenced by the correlation of the molar conductivity of the diluted solution with the salt concentration under the equation describing the state of weak electrolytes. From the transformations of experimental data in the coordinates of this equation, the values of the electrolytic dissociation constants of the studied salts were determined, which vary (8.30 ± 0.01)·10-5 to (4,35 ± 0,01)·10-8 (mol/l)2 when varying the alcohol content from 30 to 90% volume. It is shown that isopropanol additives reduce the constant (and hence the degree) of electrolytic dissociation of alkali metal sulfates: the higher the alcohol concentration in the solution, the weaker the salt becomes as an electrolyte. The value of the electrolytic dissociation constant depends on the nature of the salt: with an increase in the size of the sulfate cation, the electrolytic dissociation constant decreases.

Raman Spectroscopic Study of Ion Pairing of Alkali Metal Ions with Carbonate and Sulfate in Aqueous Solutions

2000 ◽  
Vol 53 (10) ◽  
pp. 887 ◽  
Author(s):  
Pal Sipos ◽  
Lee Bolden ◽  
Glenn Hefter ◽  
Peter M. May
Keyword(s):  
Alkali Metal ◽  
Aqueous Solutions ◽  
Ion Pairing ◽  
Electrolyte Solutions ◽  
Ionic Interactions ◽  
Alkali Metal Ions ◽  
Sulfate Ions ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Stretching Vibrations

Raman spectra of carbonate and sulfate ions were recorded in aqueous solutions in the presence of large excesses of M′X (M′+ = Na+, K+ or Cs+; X– = OH– or Cl–) at 25°C. The positions of the v1(A1′) symmetric stretching vibrations for both CO32– (at ~1060 cm–1) and SO42– (at ~980 cm–1) shift, by up to 10 cm–1, to lower frequencies and broaden (by up to 25%) with increasing concentrations of M′X. The shifts are slightly smaller for SO42– than for CO32– and also differ somewhat between M′OH and M′Cl solutions. The changes in the peak positions, which are indicative of contact ion pairing, show a clear dependence on the nature of the cation. However, the observed order, Na+ < K+ < Cs+, is directly opposite to the magnitudes of the (overall) ion-pairing constants. This anomaly is thought to be due to decreased hydration of Cs+ cf. Na+ in these highly concentrated, water-deficient solutions. Some implications of this for understanding ionic interactions in concentrated electrolyte solutions are suggested.

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