Affiliation:
1. Department of Chemistry, Kurukshetra University, Kurukshetra-136119, India
2. Department of Chemistry, Kurukshetra University, Kurukshetra-136119, India 2Department of Chemistry, Markanda National College, Shahabad Markanda-136135, India
Abstract
Ultrasonic velocities (u) and densities (ρ) of lithium perchlorate (LiClO4), sodium perchlorate (NaClO4),
sodium tetraphenylborate (NaBPh4), tetrabutylammonium tetraphenylborate (Bu4NBPh4) and
tetrabutylammonium perchlorate (Bu4NClO4) were measured in the concentration range 0.001-0.25
mol kg-1 in acetonitrile (AN) and nitromethane (NM) binary mixtures consisting of 0, 20, 40, 60, 80
and 100 mol%NM in AN at 298.15 K. The isentropic compressibility (Ks) and apparent molal isentropic
compressibility (Ks,f) values of the above salts in all solvent mixtures have been evaluated from
experimental data. Limiting apparent molal isentropic compressibilities (Ko
s,φ) for various salts were
evaluated and split into the ionic contributions (Ko
s,φ)±. The variation of (Ko
s,φ)± with solvent compositions
shows that Li+ and Na+ ions have very large negative (Ko
s,φ)± values indicating strong solvation of both
Li+ and Na+ ions in AN + NM mixtures over whole binary solvent composition range. Stronger solvation
was further observed in the intermediate compositions of AN + NM mixtures. Li+ ions, however,
showed much higher solvation as compared to Na+ ions at all compositions. The ClO4
– ions showed
feeble solvation in AN + NM mixtures through some interaction with AN binary mixtures with higher
mol% of AN. The positive values of (Ko
s,φ)± with large magnitude for Bu4N+ and Ph4B– ions indicate
solvophobic type of interaction with the solvent molecules, which is stronger in the intermediate
compositions of AN + NM mixtures.
Publisher
Asian Journal of Chemistry