THERMODYNAMIC STUDY ON THE TRANSFER OF THE TIN(II), LEAD(II) AND ALKALINE-EARTH-METAL IONS FROM WATER TO METHANOL, DIMETHYL-SULFOXIDE, ACETONITRILE, PYRIDINE AND N,N-DIMETHYLTHIOFORMAMIDE
M. Chaudhry et al., THERMODYNAMIC STUDY ON THE TRANSFER OF THE TIN(II), LEAD(II) AND ALKALINE-EARTH-METAL IONS FROM WATER TO METHANOL, DIMETHYL-SULFOXIDE, ACETONITRILE, PYRIDINE AND N,N-DIMETHYLTHIOFORMAMIDE, Journal of the Chemical Society. Faraday transactions, 90(18), 1994, pp. 2683-2689
Citations number
72
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The thermodynamic functions for the transfer reactions of the tin(II),
lead(II) and alkaline-earth-metal ions from water to methanol, aceton
itrile, dimethyl sulfoxide and pyridine, and of the tin(II) and lead(I
I) ions to N,N-dimethylthioformamide, are reported. The Gibbs energies
of transfer, Delta(t)G(-) have been calculated from the standard elec
trode potentials of the Sn2+/Sn(s) and Pb2+/Pb(s) couples, which have
been determined potentiometrically with the Ag(s)/Ag+ electrode as ref
erence in the title solvents, and the Gibbs energies of transfer of th
e silver ion. The Gibbs energies of transfer of the alkaline-earth-met
al ions were calculated from electrode or halfwave potentials of the M
(2+)/M(am) couples in the title solvents and the difference in standar
d electrode potential between the M(2+)/M(am) and M(2+)/M(s) couples r
eported in the literature. The enthalpies of transfer, Delta(t)H(e), h
ave been obtained from calorimetrically determined enthalpies of solut
ion of the anhydrous metal trifluoromethylsulfonates. The entropies of
transfer, Delta(t)S(-), have been calculated from the experimentally
determined Delta(t)G(-) and Delta(t)H(-) values. All measurements have
been carried out at 25 degrees C. The extrathermodynamic tetraphenyla
rsonium tetraphenylborate (TATB) assumption has been applied in order
to calculate the contributions from the single ions. The tin(II)) and
lead(II) ions are solvated more strongly in dimethyl sulfoxide and N,N
-dimethylthioformamide than in water, while they are solvated more wea
kly in methanol and acetonitrile. The small tin(II) ion is solvated mo
re weakly and the larger lead(II) ion is solvated more strongly in pyr
idine than in water. The alkaline-earth-metal ions are solvated more s
trongly in dimethyl sulfoxide than in water, while methanol and the ni
trogen donor solvents acetonitrile and pyridine solvate these ions mor
e weakly than water. The enthalpies of transfer for these ions to the
solvents studied are exothermic except for the tin(II), calcium and st
rontium ions to acetonitrile. The entropies of transfer to all solvent
s are markedly negative except for N,N-dimethylthioformamide where the
T Delta(t)S(-) values are close to zero. The difference in solvation
of an ion between two solvents is mainly dependent on the bonding char
acter of the ion-solvate bonds and on the way in which the ion affects
the solvent bulk.