Reply to the Comment on the Calculation of Lithium Isotope‐Exchange Equilibrium Constants

1970 ◽  
Vol 52 (6) ◽  
pp. 3313-3314 ◽  
Author(s):  
John C. Hall ◽  
P. A. Rock
Keyword(s):  
Isotope Exchange ◽  
Equilibrium Constants ◽  
Exchange Equilibrium ◽  
Lithium Isotope

scholarly journals Temperature effect on ion exchange equilibrium between CMX membrane and electrolytes solutions

2015 ◽  
Vol 5 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Akrem Chaabouni ◽  
Fatma Guesmi ◽  
Islem Louati ◽  
Chiraz Hannachi ◽  
Béchir Hamrouni
Keyword(s):  
Ion Exchange ◽  
Binary Systems ◽  
Equilibrium Constants ◽  
Exchange Process ◽  
Standard Free Energy ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Exchange Equilibrium ◽  
Standard Entropy ◽  
Ion Exchange Process

Ion exchange equilibrium for three systems involving monovalent and divalent ions has been investigated over various temperatures (283, 298 and 313 K) using CMX cationic exchange membrane. All experiments were carried out at 0.1 mol/L. Ion exchange isotherms for the binary systems (Na+/K+), (Na+/Ca2+) and (K+/Ca2+) were established at temperatures ranging from 283 to 313 K. The obtained affinity order is: K+>Ca2+>Na+. Selectivity coefficients KK+2Na+, K2Na+Ca2+ and KCa2+2K+ were determined and found to increase with rise in temperature. Thermodynamic equilibrium constants Ki°j were calculated. Wilson and Debye–Hückel equations have been used to calculate activity coefficients in the membrane and solution, respectively. Standard free energy ΔGT°, standard enthalpy change ΔHT° and standard entropy change ΔST° were calculated. The values of ΔHT° were found to be 51.98 kJ/mol, 64.59 kJ/mol and 29.57 kJ/mol, respectively, for (Na+/K+), (Na+/Ca2+) and (K+/Ca2+) binary systems, which indicate that the ion exchange process between the CMX membrane and the studied binary systems is an endothermic process. ΔST° is found to be positive, which means that the increased randomness appeared on the membrane-solution interface during the ion exchange reaction. In addition, the standard free enthalpy change ΔGT° value for all systems is negative, which is an indication that the ion exchange equilibrium is spontaneous in standard conditions.

A MASS SPECTROMETER AND THE MEASUREMENT OF ISOTOPE EXCHANGE FACTORS

1945 ◽  
Vol 23b (1) ◽  
pp. 40-47 ◽  
Author(s):  
H. G. Thode ◽  
R. L. Graham ◽  
J. A. Ziegler
Keyword(s):  
Direct Measurement ◽  
Mass Spectrometer ◽  
Isotope Exchange ◽  
Equilibrium Constants ◽  
Packed Columns ◽  
Radius Of Curvature ◽  
Column Experiments ◽  
Sulphur Isotopes ◽  
Mass Unit ◽  
Fractionation Column

A 180 degree direction focusing mass spectrometer for isotope abundance measurements is described. In operation, the instrument has a resolution of one mass unit in 100, which is the resolution expected from the dimensions of the slits and the radius of curvature of the ion path.The precision of the instrument is sufficiently good to make possible the direct measurement of equilibrium constants for many isotopic reactions. Several reactions previously used to separate the nitrogen and the sulphur isotopes have been investigated. The equilibrium constants for the two reactions[Formula: see text]were found to be about 60% higher than those previously reported from fractionation column experiments. However, the low values previously reported can be accounted for on the basis of Cohen's theory of packed columns.

Lithium Isotope Effects upon Electrochemical Release from Lithium Cobalt Oxide to Non-Lithium Electrolyte Solution

2014 ◽  
Vol 69 (1-2) ◽  
pp. 97-103 ◽  
Author(s):  
Yuta Takami ◽  
Satoshi Yanase ◽  
Takao Oi
Keyword(s):  
Cobalt Oxide ◽  
Electrolyte Solution ◽  
Ethylene Carbonate ◽  
Organic Electrolyte ◽  
Exchange Equilibrium ◽  
Lithium Cobalt Oxide ◽  
Lithium Isotope ◽  
Lithium Ions ◽  
Organic Electrolyte Solution ◽  
Lithium Cobalt

Lithium was electrochemically released from a lithium cobalt oxide (LiCoO2) cathode to an ethylene carbonate-based organic electrolyte solution containing no lithium ions, and the change in the lithium isotope composition of the cathode was measured. The 7Li/6Li isotopic ratio of the electrode was practically unchanged before and after the 45% - 62% lithium release, which meant that the lithium release accompanied no isotope preference. This result is quite contrastive to the previous one; when lithium was released to an organic electrolyte solution containing lithium ions, the 7Li/6Li ratio of the cathode became 1.018 to 1.033 times smaller than that before the release. It was induced that the kind of electrolyte solution controlled the attainment of the lithium isotope exchange equilibrium between the cathode and the electrolyte solution.

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