On the Suitability and Validity of “Reference Electrolyte” Method for the Determination of Single Ion Thermodynamic Properties in Solutions

Much advocated and supposed to be best method for the determination of the Gibbs energies of single ions in any solvent or Gibbs energies of transfer of single ions between two solvents (true for other thermodynamic properties as well) is based on thermodynamics of “reference electrolyte” TATB (tetraphenylarsoniumtetraphenylborate). TATB, composed of isoelectrical counter ions (TAHowever, all the extrathermodynamic methods including “reference electrolyte” method for the determination of single ion thermodynamic values, based on Born or modified Born equations and ionic additivity principles are defective and invalid from theoretical and practical points of view. All the single ion values in the literature are thus unreliable. Moreover, different theoretical and experimental facts make “Ph

Preparation of Some Novel Copper(I) Complexes and their Molar Conductances in Organic Solvents

Attempts have been made to prepare some novel copper(I) nitrate, sulfate, and perchlorate complexes. Molar conductances of these complexes have been measured in organic solvents like acetonitrile (AN), acetone (AC), methanol (MeOH), N,N-dimethylformamide (DMF), N,Ndimethylacetamide (DMA), and dimethylsulfoxide (DMSO) at 298 K. The molar conductance data have been analyzed to obtain limiting molar conductances (λ0) and ion association constants (KA) of the electrolytes. The results showed that all these complexes are strong electrolytes in all organic solvents. The limiting ionic molar conductances (λo± ) for various ions have been calculated using Bu4NBPh4 as reference electrolyte. The actual radii for copper(I) complex ions are very large and different in different solvents and indicate some solvation effects in each solvent system

Study of the Comparative Solvation Behaviour of Na+ and Cu+ Cations in Acetonitrile + N,N-Dimethylformamide Mixtures at 298.15 K

Viscosity and molar conductance of Bu4NBPh4, Bu4NClO4, [Cu(CH3CN)4]ClO4, NaClO4 and NaBPh4 have been measured in the concentration ranges 0.02 - 0.5 mol dm−3 and 0.0005 - 0.0065 mol dm−3 at 298.15 K in AN + DMF mixtures containing 0, 10, 20, 40, 60, 75, 80, 90, and 100 mol % DMF. The viscosity data have been analyzed by the extended form of the Jones-Dole equation in the form: (η/η0) = 1+AC1/2+BC+DC2 to evaluate B and D parameters and the conductance data by the Shedlovsky equation to evaluate Λo and KA values of the salts. Ionic viscosity B-coefficients (B±) and ionic molar conductances (λ◦ i) have been calculated by using Bu4NBPh4 as a reference electrolyte. Solvated radii (ri) for Na+, Cu+ and ClO4 − have been estimated by using Gill’s modification of Stokes’ law. The variation of B± and ri as a function of mol % DMF shows that both Na+ and Cu+ are highly solvated in AN + DMF mixtures over the entire composition region. The solvation passes through a maximum between 40 to 80 mol % DMF. Both Na+ and Cu+ are more strongly solvated between 40 to 80 mol % DMF. Cu+ is relatively more strongly solvated than Na+ in AN + DMF mixtures. ClO4 − shows poor solvation in AN + DMF mixtures.

Behaviour of Some Copper(I) and Cobalt(III) Complexes in Acetonitrile and n-Butyronitrile at 298.15K

Molar conductances of a large number of copper(I) and cobalt(III) complexes, behaving as strong 1:1 electrolytes, have been measured in acetonitrile (AN) and n-butyronitrile (n-BTN) at 298.15K. The conductance data have been analyzed by the Shedlovsky method to evaluate Λ0 and KA values of these electrolytes. Limiting ion conductances (λi0) for various ions in AN have been calculated by using transference number data. In n-BTN, where no transference number data is available, such values have been calculated by an indirect method using Bu4NBPh4 as a reference electrolyte. The actual ionic radii (ri) for various ions in solution have been calculated using a modified form of Stokes’ law. The ionic radii (ri) for various complex ions have been compared with the ionic radii of two reference ions, Bu4N+ and Ph4B−, which are not solvated in dipolar aprotic solvents, to throw light on the solvation behaviour of these complex ions.

Solubility and Thermodynamic Transfer Functions of Cesium Dianilinetetraisothiocyanatochromate(III)

The solubilities of cesium dianilinetetraisothiocyanatochromate(III) in water as well as in aqueous methanol, isopropyl alcohol, tert-butyl alcohol and acetonitrile were measured as a function of temperature and solvent composition. The Gibbs energies, enthalpies and entropies of transfer of the salt from water to the given solvents have been evaluated from experimental data. The contribution of [Cr(C6H5NH2)2(NCS)4]- ion to the Gibbs energy of transfer of the investigated salt has been calculated using the tetraphenylarsonium tetraphenylborate (TATB) reference electrolyte assumption.

Gibbs Transfer Energies of Some Uni-Univalent Salts in Water—N-Methyl-2-Pyrrolidinone Solvent Mixtures at 30°C

The standard Gibbs transfer energies of some uni-univalent electrolytes like potassium picrate, tetraphenylarsonium picrate, potassium and silver tetraphenyl borate were determined in water + N-Methyl-2-Pyrrolidinone mixtures from solubility measurements at 30 °C. They were split into respective ionic values on the basis of the reference electrolyte method using tetraphenylarsonium tetraphenylborate. The variation of transfer energies of the ions with composition of solvent are examined and discussed in terms of the possible ion-solvent interactions.

Gibbs Transfer Energies and Solvent Transport Numbers of Some Copper(II) Salts in Methanol-Dimethylformamide Mixtures

Standard Gibbs energies of transfer have been determined for copper(II) iodate, benzoate and formate at 30°C in methanol- dimethylformamide mixtures by solubility measurements. Single-ion transfer energies were obtained by using the negligible liquid junction potential assumption, along with relevant literature data, and are in excellent agreement with values estimated from the reference electrolyte ( tatb ) assumption. The results obtained indicate that all of these salts are heteroselectively solvated in these mixtures, with Cu2+ being preferentially solvated by dmf and the anions by MeOH. This model is consistent with calculations based on the quasi-lattice quasi-chemical theory of Marcus and with solvent transport numbers obtained from e.m.f . measurements.

Viscosity Studies of Some Electrolytes in Dimethyl Sulfoxide and N,N-Dimethylformamide at Different Temperatures

The limiting molar conductivity Λ0 and the Jones-Dole viscosity coefficients A and B were measured for Ph4PBPh4, Bu4NBPh4, Bu4NClO4, Ph4PBr, Bu4NBr, NaBPh4, NaClO4, KClO4, LiClO4 and AgClO4 in pure DMF and DMSO at 20, 30 and 40 °C. The experimental coefficients A are compared with the coefficients A calculated from the Falkenhagen-Vernon equation. The ionic viscosity coefficients B, which were obtained using Ph4PBPh4 as the reference electrolyte, are discussed in terms of the contributions in the expression: Bion = Bw + Bsolv + Bord + Bdisord + Bshape.

Thermodynamic behaviour of some electrolytes in ethane-1,2-diol from −10 to +80 °C

Conductivities of the electrolytes NaBr, NaPi, HPi, NaBPh4, and Ph4PBr in ethane- 1,2-diol were determined in the −10 ≤ t ≤ +80 °C temperature range. The experimental data were analyzed by the Fuoss–Hsia equation, which provides further informative parameters such as the dissociation constant (K) of the ion pairs formed in solution, the limiting equivalent conductivity (Λ0), and the ion-size parameter (å). Thermodynamic behaviour of these electrolytes was derived from analysis of the K values. Single-ion conductivities were evaluated on the basis of the assumption of Ph4PBPh4 as reference electrolyte.