M. Shamsuddin Ahmed

Density and Viscosity of 1-Alkanols

Densities and viscosities have been measured for twelve 1-alkanols from methanol to 1-dodecanol at temperatures ranging from 303.15 to 323.15 K. Molar volumes, V m , have been calculated from the density data, which have been found to follow the additive equation, V m  = V CH3  + nV CH2  + V OH, where n is the number of CH2 groups. V m have been plotted against n, showing an excellent linear relationship. The average values of V CH2 at 303.15 K and 323.15 K have been determined from the slopes of this equation. The viscosities have been found to increase almost exponentially with the number of carbon atoms at different temperatures. The thermodynamic activation parameters, free energy, ▵G ≠, enthalpy, ▵H ≠, and entropy, ▵S ≠ for viscous flow have been plotted against the number of C atoms – all have been found to increase with the chain length of 1-alkanols.

Excess Molar Volumes and Thermal Expansivities of Aqueous Solutions of Dimethylsulfoxide, Tetrahydrofuran and 1,4-Dioxane

Densities, , of the systems water (W) + dimethylsulfoxide (DMSO), W + tetrahydrofuran (THF) and W + 1,4-dioxane (DO) have been determined in the temperature range 303.15-323.15 K. Excess molar volumes,

Viscosity and Excess Viscosity of Dilute Aqueous Solutions of Ethylenediamine, Trimethylenediamine and N , N -Dimethyltrimethylenediamine

V_m^E

Density, viscosity and thermodynamic activation for viscous flow of water+sulfolane

, have been found to be negative and large in magnitude. Thermal expansivities, f , and excess thermal expansivities, f E , have been calculated. Densities, excess molar volumes, thermal expansivities and excess thermal expansivities have been plotted against mole fraction of solutes. All these properties have been expressed satisfactorily by appropriate polynomials. Attempt has been made to explain

Viscosities of Aqueous Solutions of Dimethylsulfoxide, 1,4-Dioxane and Tetrahydrofuran

V_m^E

Excess molar volumes and viscosities of some alkanols with cumene

in terms of hydrophobic hydration and hydrophilic effect of the solutes.

Viscosity of aqueous solutions of some diamines

Viscosities of the systems, water (W) + ethylenediamine (ED), W + trimethylenediamine (TMD) and W + N , N -dimethyltrimethylenediamine (DMTMD) were determined from 303.15 to 323.15 K and in the composition range, 0 h X 2 h 0.45, where X 2 is the mole fraction of solutes. On addition of the solutes to water the viscosities increase sharply, pass through maxima and then decline; the heights of maxima vary as, W + DMTMD > W + TMD > W + ED. The maxima occur at X 2 0.225, 0.300 and 0.325 for the systems, W + DMTMD, W + TMD and W + ED, respectively. The position of maximum of a particular system remains unchanged with temperature. The rapidly ascending part of viscosity curves is accounted for by the combined effect of hydrophobic hydration and hydrophilic effect, while the declining part of the curves is thought to be due to predominance of hydrophobic interaction.

Density, viscosity and thermodynamic activation of viscous flow of water + acetonitrile

Densities and viscosities for the system, water (W) + sulfolane (SFL), have been determined for the entire range of composition at temperatures ranging from 303.15 to 323.15 K. Density, excess molar volume, viscosity, excess viscosity and thermodynamic activation parameters for viscous flow have been calculated and plotted against the mole fraction of SFL. The measured properties and some of the derived properties have been fitted to appropriate polynomial equations. These have been explained in terms of such factors, as, dipole–dipole interaction, partial accommodation of water molecules into the structural network of SFL and H-bonding between SFL and H2O.

Viscous flow of aqueous solutions of some alcohols

Abstract Viscosities of the systems, water(W) + dimethylsulfoxide(DMSO), W + 1,4-dioxane (DXN) and W + tetrahydrofuran(THF), are measured at temperatures ranging from 303.15–323.15K. Viscosities and excess viscosities are plotted against the mole fraction of the organic solutes. On addition of solutes to water, viscosities first increase rapidly, pass through maxima and then decline continuously until the pure state of solutes is reached. Excess viscosities are found to be positive and large in magnitude and their curves are similar to those of the viscosity curves. The ascending part of the viscosity curves in the water-rich region is accounted for by both the hydrophobic effect of forming cage structures around solutes and the hydrophilic effect forming H-bonds between water and organic solutes. The descending part of the viscosity curves is explained by the continuous destruction of cages formed. The maxima are thought to be due to competing processes of formation and destruction of cage structures.

Viscosity of the systems m-xylene, +1-propanol, +2-propanol, +1-butanol, +t-butanol

Densities, ρ, viscosities, η, of the systems, cumene + 1-propanol, +2-propanol, +1-butanol and +t-butanol, have been determined from 303.15 to 323.15 K, with an interval of 5 K. Excess molar volumes, , and excess viscosities, ηE, have been calculated from density and viscosity data. ρ, , η and ηE of the systems have been plotted against the mole fraction of alcohols. Some of these properties and their excess values have been represented satisfactorily by appropriate polynomials. For the systems, cumene + 1-propanol and cumene + 1-butanol, are both positive and negative, but for the systems, cumene + 2-propanol and cumene + t-butanol, positive have been observed for the whole range of composition. The observed volumetric and viscometric properties have been explained by the concepts: (a) dissociation of alkanols in cumene-rich region, (b) partial accommodation of cumene into interstitial positions of 1-alkanols in alkanol-rich region, (c) donor–acceptor interaction between alkanols and cumene and (d) steric hindrance of branched alkanols.