Molecular interaction studies on the binding ability of hydrated zinc sulphate with aqueous solution of ascorbic acid at different temperatures

The ternary systems containing Water, Ascorbic acid (AA) and ZnSO4·7H2O were investigated using three approaches namely volumetric studies, viscosity studies and conductance studies. The solvent systems used were 2, 4 and 6% (by weight) of AA in water. The studies were conducted at four temperatures (303.15–318.15 K with an interval of 5 K) and pressure 0.1 MPa with concentration of ZnSO4·7H2O in the solution ranging from 0.01 to 0.12 m. Various parameters like partial molar volume (ϕ v), apparent molar volume ( ϕ v o ) $({\phi }_{\text{v}}^{\text{o}})$ , Hepler’s constant ( ( d 2 ϕ v o / d T 2 ) p ) $({({d}^{2}{\phi }_{\text{v}}^{\text{o}}/d{T}^{2})}_{p})$ , partial molar expansibility ( ϕ E o ) $({\phi }_{\text{E}}^{\text{o}})$ and transfer volume ( Δ t r ϕ v o ) $({{\Delta}}_{tr}{\phi }_{\text{v}}^{\text{o}})$ have been evaluated from volumetric studies. The viscosity studies have yielded Jones-Dole parameters (A and B) and free energy of activation per mole for solvent ( Δ μ 1 0 ‡ ) $({\Delta}{\mu }_{1}^{0{\ddagger}})$ and solute ( Δ μ 2 0 ‡ ) $({\Delta}{\mu }_{2}^{0{\ddagger}})$ . The conductance data has been used to calculate molar conductance (Λm), limiting molar conductance ( Λ m o ) $({{\Lambda}}_{\text{m}}^{\text{o}})$ and Walden product ( Λ m o η o ) $({{\Lambda}}_{\text{m}}^{\text{o}}{\eta }_{\text{o}})$ . The results of these studies agree with each other and have concluded the structure breaker behavior of ZnSO4·7H2O in the solvent system containing AA and water.

Molecular interaction investigation of some alkaline earth metal salts in aqueous citric acid at various temperatures by physiochemical studies

Densities, ultrasonic velocity, conductance and viscosity of some alkaline earth metal chlorides such as magnesium chloride (MgCl2) and calcium chloride (CaCl2) were calculated in the concentration range (0.01–0.12 mol kg−1) in 0.01 mol kg−1 aqueous solution of citric acid (CA + H2O) at four varying temperatures T 1 = 303.15 K, T 2 = 308.15 K, T 3 = 313.15 K and T 4 = 318.15 K. The parameters like apparent molar volume (ϕ v ), limiting apparent molar volume ( ϕ v o ${\phi }_{v}^{o}$ ) and transfer volume (Δtr ϕ v o ${\phi }_{v}^{o}$ ) were calculated from density data. Viscosity data have been employed to calculate Falkenhagen coefficient (A), Jone–Dole’s coefficient (B), relative viscosity (η r ), and relaxation time (τ) whereas limiting molar conductance ( Λ m o ${{\Lambda}}_{m}^{o}$ ) has been evaluated from conductance studies. Using these parameters, various type of interactions occurred in the molecules have been discussed. Values of Hepler’s constant (d 2 ϕ v o ${\phi }_{v}^{o}$ /dT 2) p , (dB/dT) and d( Λ m o ${{\Lambda}}_{m}^{o}$ η o )/dT suggests that both MgCl2 and CaCl2 behave as structure breaker in (CA + H2O) system. The positive value of transfer volume exclusively tells about solute–solvent interactions which further indicate that both metal chlorides distort the structure of water and act as structure breaker. These studies are helpful in understanding the nature of interactions occurs in biological systems as CA and metal salts are essential for normal functioning of body.

Interactions of Drug Doxycycline Hyclate with Galactitol in Aqueous Solutions at Different Temperatures by Volumetric and Acoustic Methods

The experimental values of density, ρ and speed of sound, u of doxycycline hyclate drug (0.002–0.014) mol kg−1 in water and (0.1, 0.2 and 0.4) mol kg−1 of aqueous galactitol solutions at temperatures T = (303.15, 308.15 and 313.15) K and at atmospheric pressure have been reported in the present communication. From the experimental values, various derived parameters such as apparent molar volume (Φ V), apparent molar isentropic compression (Φ K), limiting apparent molar volume ( Φ v o $\phi_{\text{v}}^{\text{o}}$ ), limiting apparent molar isentropic compression ( Φ K o $\phi_{\text{K}}^{\text{o}}$ ), limiting apparent molar volume of transfer (Δ Φ V O $\phi_{\text{V}}^{\text{O}}$ ), limiting apparent molar isentropic compression of transfer (Δ Φ K O $\phi_{\text{K}}^{\text{O}}$ ), limiting apparent molar expansibility ( Φ E o $\phi_{\text{E}}^{\text{o}}$ ), thermal expansion coefficient (α) and acoustic parameters like isentropic compressibility ( κ S ) $({{\kappa}_{\text{S}}})$ , intermolecular free length (Lf), and specific acoustic impedance (Z) were calculated. The structure-making behaviour of DH in aqueous galactitol solution was determined on the basis of Hepler’s Equation i.e. on the basis of sign of ( d 2 Φ V O d T 2 ) P ${\left({\frac{{{{\text{d}}^{2}}\phi_{\text{V}}^{\text{O}}}}{{{\text{d}}{{\text{T}}^{2}}}}}\right)_{\text{P}}}$ . The various derived parameters were utilised to interpret the molecular interactions i.e. solute–solute and solute–solvent existing in the studied system.

Volumetric, Viscosity and Conductance Studies of Solute–Solute and Solute–Solvent Interactions of Some Alkali Metal Chlorides in Aqueous Citric Acid at Different Temperatures

The present study aims for the structure-making and structure-breaking behavior of some electrolytes in aqueous citric acid solution. The density, viscosity and conductance of some alkali metal chlorides lithium chloride (LiCl), sodium chloride (NaCl) and potassium chloride (KCl) in 0.01 m aqueous citric acid have been measured in the concentration range 0.01–0.12 m at 303.15, 308.15, 313.15 and 318.15 K. From these measurements, molar volume, viscosity parameters and molar conductance have been deliberated. Debye Hückel limiting law is used for the assessment of the contributions of various types of solute–solvent interactions. Jones–Dole viscosity equation is used to calculate viscosity B-coefficient for these salts in aqueous citric acid, which is known to provide information concerning the solvation of ions and their effects on the structure of the solvent in the near environment of the solute particles. The free energies of activation of viscous flow per mole of solvent, Δ μ 1 0 ‡ $\Delta \mu _1^{0\ddagger }$ and solute, Δ μ 2 0 ‡ , $\Delta \mu _2^{0\ddagger },$ have also been evaluated by using viscosity data. Using molar volume, the transfer volume Фv o tr has also been computed. The structure making/ breaking behavior of LiCl, NaCl and KCl is inferred from the sign of second derivative of partial molar volume with respect to temperature at constant pressure (d2φv o/dT2)p, Temperature coefficient of B. dB/dT and temperature coefficient of Walden product i.e. d(Λm oηo)/dT values. It has been found from these studies that LiCl, NaCl and KCl behave as structure-breaker in 0.01 m aqueous citric acid solution. The results have been qualitatively used to explain the molecular interaction and structural changes between the components of these mixtures.