Mandeep Singh Bakshi

Cetylpyridinium chloride–tetradecyltrimethylammonium bromide mixed micelles in ethylene glycol–water and diethylene glycol–water mixtures

The conductances of cetylpyridinium chloride (CPyCl)–tetradecyltrimethylammonium bromide (TTAB) mixtures over the entire mole fraction range of CPyCl (xCPyCl) have been measured in water, ethylene glycol–water (EG–W) and diethylene glycol–water (DEG–W) mixtures consisting of 20, 40 and 60 wt.% EG and DEG in their respective binary mixtures at 30 °C. From the conductivity data, the mixed critical micellar concentration (cmc), degree of counter-ion dissociation (χ), standard Gibbs energy of transfer of the surfactant hydrocarbon chain from medium to the micelle (ΔGHP°), and Gibbs energy of transfer of surface contributions (ΔGs°) for mixed micelles were computed. The non-ideality in the mixed micelle formation was evaluated by using the regular solution theory extended by Rubingh. It was observed that the non-ideality decreases with increase in the amount of EG or DEG. This was attributed to the solvation of the surfactant hydrophobic tail by EG or DEG molecules owing to EG or DEG–hydrocarbon interactions.

Thermodynamic behaviour of mixtures. Part 1.—Mixtures of pyridine with β-picoline, γ-picoline, isoquinoline, benzene and cyclohexane at 25 °C

Ultrasonic velocities (u) and densities (ρ) of mixtures of pyridine (Py) with β-picoline, γ-picoline, isoquinoline, benzene and cyclohexane have been measured over the whole composition range at 25 °C. From u and ρ data, various intermolecular interaction parameters such as Wadas constant (W), the molar sound velocity (um) and the solvation number of the co-solvent (Nc) have been calculated for these binary systems. The partial molar volumes (text-decoration:overlineV0) and isentropic compressibilities (text-decoration:overlineκ0s) at infinite dilution have also been computed for all the cosolvents as well as for Py. The variation of the excess properties VE and κEs shows that Py–β-picoline and Py–γ-picoline have mild excess contributions in comparison to all other Py–co-solvent systems. The excess contributions for Py–isoquinoline and Py–benzene have been attributed to the strong specific interactions and that of Py–cyclohexane to the strong dispersive forces that operate between the components of the binary mixtures.

Transport properties of copper(I) perchlorates in mixed solvents. Part 1.—Transference numbers of copper(I) perchlorate in acetonitrile–N,N-dimethylacetamide mixtures at 25 °C

Transference numbers of Cu+ and ClO–4 ions in copper(I) perchlorate (CuClO4) have been measured in acetonitrile–N,N-dimethylacetamide mixtures containing 90, 80, 70, 60, 50 and 40 mol% acetonitrile at 25 °C. The limiting transference numbers of Cu+(t0Cu+) in various solvent mixtures have been evaluated using the modified Longsworth method. λ0Cu+ and λClO4–0 values have been calculated by combining limiting transference numbers of the Cu+ cation with the Λ0 values of CuClO4, and the solvated radii for Cu+ and ClO–4 ions have been evaluated. Comparison of the solvated radii for the Cu+ and ClO–4 ions in acetonitrile–N,N-dimethylacetamide (AN–DMA) and acetonitrile–N,N-dimethylformamide (AN–DMF) mixtures shows an identical solvation behaviour of the ClO–4 ion in these two solvent systems, but relatively more solvation of the Cu+ cation in AN–DMF mixtures.

Thermodynamic behaviour of mixtures. Part 2.—Mixtures of acetonitrile with β-picoline, γ-picoline, 2,6-lutidine, isoquinoline and benzene at 25 °C

Ultrasonic velocities (u), densities (ρ), static relative permittivities (Iµ) and refractive indices (nD) of mixtures of acetonitrile (AN) with β-picoline, γ-picoline, 2,6-lutidine, isoquinoline and benzene have been measured over the entire composition range at 25 °C. Intermolecular interaction parameters, such as the molar sound velocity (um) and the solvation number of the co-solvent (Nc) have been calculated for all the binary mixtures. The partial molar volumes (text-decoration:overlineV0) and the partial isentropic compressibilities (text-decoration:overlineκ0S) at infinite dilution have been calculated for all the co-solvents as well as for AN. Excess properties, such as the excess isentropic compressibility (κES), volume (VE), relative permittivity (ΔIµ), molar polarisation (PE) and molar refraction (RE) have also been computed for these binary mixtures. Weak specific interactions are present between the components of AN–β-picoline and AN–γ-picoline in comparison to all other AN–base mixtures.

Transport properties of copper(I) perchlorates in mixed solvents. Part 2.—Conductance and viscosity measurements of bis(2,9-dimethyl-1, 10-phenanthroline)copper(I) perchlorate in binary solvent mixtures containing acetonitrile

Conductance and viscosity of bis(2,9-dimethyl-1, 10-phenanthroline)copper(I) perchlorate ([Cu(DMphen)2]ClO4) have been measured in the concentration range (0.6–6)× 10–4 mol dm–3 and (6–250)× 10– mol dm–3, respectively, at 25 °C in acetonitrile–water (AN–H2O), acetonitrile–methanol (AN–MeOH), acetonitrile–acetone (AN–AC) and acetonitrile–N,N-dimethylformamide (AN–DMF) mixtures containing 100, 90, 80, 70, 60, 50, 40, 30, 20, 10 and 0 mol% acetonitrile. The conductance and viscosity data have been analysed by the Shedlovsky and Jones–Dole equations, respectively. The limiting ion conductances of the [Cu(DMphen)2]+ cation in various solvent systems have been evaluated by combining Λo values of [Cu(DMphen)2]ClO4 with the accurate λClO4–O values obtained from our previous studies. The viscosity B coefficients of the salt in various solvent systems have been evaluated and split into the component contributions of [Cu(DMphen)2]+ and ClO–4 ions. The solvated radius (ri) for the [Cu(DMphen)2]+ cation in AN–H2O, AN–MeOH, AN–AC and AN–DMF mixtures remains nearly constant, indicating the same extent of solvation in all of these solvent systems. The solvation of this cation is, however, stronger in pure AN than in mixed solvents.

Transference number measurements of silver nitrate in pure and mixed solvents using the electromotive force method

Transference numbers of NO–3(tNO–3) and Ag+(tAg+) in AgNO3 have been measured at several concentrations in the range 0.01538–0.2000 mol dm–3 in N,N-dimethylacetamide (DMA), pyridine (Py) and in acetonitrile (AN)–DMA, AN–Py, AN–nitrobenzene (NB) and methanol (MeOH)–N,N-dimethylformamide (DMF) mixtures containing 20, 40, 60 and 80 mol % AN or MeOH at 25 °C usiong the e.m.f. method. The transference numbers show practically no concentration dependence on AgNO3 in DMA and in AN–DMA mixtures but a significant concentration dependence in all other cases. The limiting transference numbers of Ag+(t°Ag+) in the former cases have been obtained by calculating the average of practically constant values of transference numbers of Ag+ at different AgNO3 concentrations while in all other cases by using the Longsworth method in the form suggested by Kay and Dye. The t°Ag+ values in various solvent mixtures have been found to vary significantly with the solvent composition. The λ°Ag+ and λ°NO3– values have been obtained in all the solvent systems studied by combining Λ0 values of AgNO3 with the present t°Ag+ values. The plots of the Walden product for Ag+ and NO–3 as a function of solvent composition show preferential solvation of Ag+ and NO–3 by specific solvents in these mixed solvents.

EMF Measurements of AgNO3 Transference Numbers in Mixtures of Acetonitrile and N,N-Dimethylformamide at Different Temperatures

Transference numbers of AgN03 have been measured in the concentration range 0.01538 to 0.2000 mol dm~3 in mixtures of acetonitrile (AN) and N,N-dimethylformamide (DMF) containing 0, 20, 40, 60, 80 and 100 mol% AN at 15, 20, 30, 35 and 40°C using the emf method. The transference numbers of NOf (?noj-) at all temperatures are found to be almost independent of the AgN03 concentration. The limiting transference numbers Cnoj ) have been determined by averaging the almost constant transference number values at various AgN03 concentrations. The limiting transference numbers of N03 in (AN + DMF) mixtures vary significantly with solvent composition and temperature.

Transference number, conductance and viscosity studies of some 1 : 1 electrolytes in pyridine–methanol mixtures at 25 °C

Transference numbers of NO–3(tNO–3) in AgNO3 have been measured at several concentrations in the range 0.01538–0.2000 mol dm–3 in pyridine–methanol (Py–MeOH) mixtures containing 90, 70, 40 and 10 mol % Py at 25 °C using the e.m.f. method. The limiting transference numbers of Ag+(t°Ag+) in all cases have been obtained by applying the Logsworth method in the form suggested by Kay and Dye. The t°Ag+ value in Py–MeOH mixtures varies significantly with the solvent composition. Molar conductances and viscosities of Bu4NBPh4, Bu4NClO4, Bu4NI, NaClO4, NaBPh4,CuClO4·4AN, AgClO4 and AgNO3 in Py–MeOH mixtures have also been measured in the concentration range (1–68)× 10–4 and (17–655)× 10–4 mol dm–3 respectively, at 25 °C. The conductance data by the Jones–Dole equation for the unassociated as well as for the associated electrolytes. The A and B coefficients of the Jones–Dole equation are positive in all cases. The A coefficients are in reasonably good agreement with the limiting theoretical values (Aη) calculated by using Falkenhagen–Vernon equation. The limiting-ion conductances for Ag+(λ°Ag+) in Py–MeOH mixtures have been obtained by combining the Λ0 value of AgNO3 with t°Ag+. Using λ°Ag+ in various solvent systems studied, the λ°i values for several other ions have been computed. The variation of the actual solvated radii (ri) as well as the ionic B+ and B– coefficients with the solvent composition in Py–MeOH mixtures shows a heteroselective preferential solvation of AgNO3, AgClO4 and CuClO4 with the cations preferentially solvated by Py and the anions preferentially solvated by MeOH. NaClO4, however, shows a homoselective preferential solvation in Py–MeOH mixtures, with both Na+ adn ClO–4 ions preferentially solvated by MeOH in the MeOH-rich region of the mixtures.

Transference number and conductance studies of AgNO3 in water–organic solvent mixtures at 25 °C

Transference numbers and molar conductance of AgNO3 have been measured at 25 °C in mixtures of water with methanol (MeOH), acetone (Ac), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO) and pyridine (Py) with 20 mol% intervals. The limiting transference numbers of NO–3 ion ([graphic omitted]) and limiting molar conductance (Λ,0) for AgNO3 in various solvent systems have been determined. The limiting ionic conductances (λ0i) and Walden product (λ0iη) for Ag+ and NO–3 ions have been computed. The variation of Walden product for Ag+ and NO–3 ions as a function of solvent composition indicates preferential solvation of Ag+ cation by the co-solvent in H2O–DMA, H2O–DMF, H2O–DMSO and H2O–Py mixtures and the preferential hydration in H2O–MeOH and H2O–Ac mixtures. The NO–3 ion is preferentially hydrated in all these solvent mixtures.