The Solvation of Cations in Nonaqueous Solvents from the Effect of Solvent Change on the Potential of Clay Membrane Electrode
| Main Authors: | M. Adhikari, S. K. Mukherjee |
|---|---|
| Format: | Article Journal |
| Bahasa: | eng |
| Terbitan: |
, 1970
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/6457924 |
Daftar Isi:
- The change in the value of "mobility ratio" and hence of the standard electrode potential Eo in solution was measured with variation of mole fraction of water in a mixture of ethanol/water, methanol/water and glycol/water by using clay membrane electrode which separates two solutions of the same K+ activity but different water activity. By suitable extrapolation in the change in Eo in solution from 100% water to 100% ethanol, methanol and glycol was estimated. The respective values of free energy change for change of solvent relative to H+ were -0·92 and +·25 Kcal. for the ethanol and methanol systems but practically zero for the glycol system. From this relative free energy change, absolute free energy change with change in medium was evaluated and were found to be - 6·32 and - 5·55 Kcal for ethanol and methanol and by using Born equation the solvated ionic radius of K+ in these nonaqueous solvents was calculated. The solvated ionic radii of K+ in ethanol and methanol were found to be 13·45 Å and 9·98 Å respectively. With glycol apparently no change in hydrated K+ ion radius takes place, suggesting that glycol owing to its large diameter is unable to replace the hydration layer around K+.