Sanjeev Maken

Molar excess Gibbs free energy of 1-Propanol or 2-Propanol + aromatic hydrocarbons at 298.15 K in terms of an association model with a Flory contribution term

Molar excess Gibbs free energy of mixing values for 1-propanol or 2-propanol + benzene, toluene, o- m- or p-xylene at 298.15 K have been calculated by the Barker method from vapour pressure data measured by a static method. The free energies of mixing for these binary systems are also predicted in terms of the Mecke-Kempter type of association model with a Flory contribution term using two interaction parameters. The predicted values agree reasonably well with the experimental values.

Excess enthalpies and volumes of mixing of 1-propanol or 2-propanol + cyclohexane at 298.15 and 308.15 K

Abstract Excess molar enthalpies and excess molar volumes at 298.15 and 308.15 K are reported for 1-propanol or 2-propanol with cyclohexane. The analysis in terms of Mecke-Kempter association model with a Flory contribution term and generalized quasi-lattice model by Barker is described.

Thermochemical investigations of associated solutions. 10. Excess enthalpies and excess volumes of ternary acetone + bromoform + n-hexane mixtures

Excess molar vohtmes and excess enthalpies are reported for binary acetone+ n-hexane, bromoform + n-hexane and acetone + bromoform mixtures, and for the ternary acetone + bromofotm+ n-hexane system at 308.15 K. Results of these measurements are used to test the applications and limitations of a newly derived conventional non-electrolyte associated solution model. The genera1 model assumes that the Gibbs free energy, excess volume and excess enthalpy can be separated into a chemical and physical contribution. The chemical interaction term results from the formation of molecular complexes and the physical contribution describes non-specific interactions between the uncomplexed and associated species in solution. Six binary interaction parameters are initially needed to describe all the binary non-specific interactions present. Simplifying approximations and mathematical manipulations reduces the number of binary interaction parameters to only three values. For many years the chemical industry has recognized the importance of thermodynamic and physical properties in design calculations involving chemical separations, fluid flow and heat transfer. The development of flow calorimeters, continuous dilution dilatometers and vibrating-tube densimeters has enabled the experimental determination of excess enthalpies, heat capacities and volumes of non-electrolyte liquid mixtures with convenience and accuracy. The utilization of continuous dilution methods, combined with modern chromatographic head-space sampling techniques, has reduced

Excess molar enthalpies of mixing of 1-propanol or 2-propanol with aromatic hydrocarbons at 308.15 K in terms of an association model

Heat of mixing data for 1-propanol or 2-propanol with benzene, toluene, o-xylene, m-xylene and p-xylene at 308.15 K have been reported. The analysis in terms of the Mecke-Kempter association model with a Flory contribution term and generalized quasi-lattice model by Barker is described.

Excess heat of mixing of 1-propanol or 2-propanol with benzene, toluene, o-, m- and p-xylenes at 298.15 K

Excess heat of mixing data at 298.15 K for 1-propanol or 2-propanol with benzene, toluene, o-xylene, m-xylene or p-xylene have been reported. Analysis in terms of the Mecke-Kempter association model with a Flory contribution term and generalized quasi-lattice model by Barker is described.

Molar excess free energy of mixing of 1-propanol or 2-propanol with cyclohexane at 298.15 and 308.15 K in terms of association model with a Flory contribution term

Excess molar Gibbs free energies of mixing for 1-propanol or 2-propanol + cyclohexane over the whole composition range at 298.15 and 308.15 K have been calculated from vapour pressure data measured by static method. The data have been analysed in terms of a Mecke-Kempter association model with a Flory contribution term.

The influence of anhydrous cupric chloride on the nature of the interactions between bromoform and 1,4-dioxane

Abstract Singh P.P. and Maken S., 1992. The influence of anhydrous cupric chloride on the nature of the interactions between bromoform and 1,4-dioxane. Fluid Phase Equilibria , 72: 299-308. Molar excess volumes, V e , and molar excess enthalpies, H e of 1,4-dioxane (D) saturated with anhydrous cupric chloride (S) (i.e. D which the complex D(S) in the liquid phase) + bromoform (BF) mixtures have been measured at 308.15 K. V e data have been analysed using the graph-theoretical model, and H E data using the ideal associated model (Hepler-Fenby) approaches. The analyses suggest that the presence of CuCl 2 in the mixture results in the formation of an associated complex, D(S), of S and D which interacts more strongly with BF than pure D. These conclusions have further been supported by NMR data of this mixture. The geometry of the D(S) and D(S) BF molecular entities have also been investigated.

Thermodynamic properties of ternary non-electrolyte solutions. Part 3.—Excess molar volumes of 2-propanone–tribromomethane–alkane mixtures

Excess molar volumes are reported for ternary 2-propanone–tribromomethane–cyclohexane, 2-propanone–tribromomethane–n-heptane and 2-propanone–tribromomethane–n-decane mixtures at 308.15 K, as well as volumetric data for the seven sub-binary systems. Results of these measurements are used to test the applications and limitations of two previously derived associated solution models. For the most part, experimental and predicted values were in reasonably good agreement. Large deviations were noted for a few ternary compositions studied, however, suggesting that non-specific interactions are important in the binary 2-propanone–tribromomethane system and should be included in any subsequent re-evaluation of the equilibrium constant and standard reaction volume.

Thermodynamics of binary mixtures of non-electrolytes containing a salt

Molar excess volume VE and enthalpy HE data have been measured at 25°C for pyridine A saturated with anhydrous cupric chloride (S) [A(S)]+ B [where B is aniline or o-toluidine (OT) or formamide (FD) or N, N-dimethylformamide (NND)] mixtures on the assumption that while the standard state of B is that of pure components B, the standard state of A(S) is that of A saturated with the salt S. The excess volume or enthalpy data for an equimolar mixture at a given temperature have been utilized to evaluate the interactional parameter X12 of the Sanchez and Lacombe theory of fluid mixtures at that temperature, and the same has been combined with VE(xA) data for a good prediction not only of the coresponding HE(xA) data for the mixture but also the extent of unlike interactions between the A(S) and B components of these A(S)+B mixtures.

Anodic oxidation of niobium in aqueous solution of weak organic acids

Abstract Steady state kinetic data for the anodic growth of films on niobium in 0.1 N oxalic, citric and tartaric acid at different temperatures and current densities (CDs) have been obtained. The breakdown voltage of oxide films on niobium has been found to be within the range 210–290 V in oxalic acid solution, 210–355 V in tartaric acid solution and 220–355 V in citric acid solution. It depends on both CD and temperature. The constants (A and B) of Guntherschulze and Betz for the empirical relation between the ionic CD and the field have been found to depend on the nature of the electrolyte. The constant A is temperature dependent while B is temperature independent. The Tafel slope has been found to be independent of the temperature range studied. Dignams quadratic variation of field with ionic current density was examined critically and φ, the zero field activation energy, C, the dimensionless constant, μ∗, the zero-field activation dipole, W(E), the net activation energy, ω∗, the Morse function parameter and i0, the current density were evaluated. It has been found that μ∗, ω∗ and i0 are temperature dependent whereas φ, W(E) and C are temperature independent. All these parameters depend on the nature of the electrolyte. The quantity W(E) does not depend on CD while φ and C change slightly and μ∗, ω∗ and i0 change markedly with changing CD. An appreciable contribution (22%–28%) of the quadratic term has been observed. Single-barrier theories of ionic conduction are not suitable for the present data.