Aqueous Solutions Of Magnesium Acetate Research Articles

Effect of Sodium Acetate and Magnesium Acetate on the Solution Behavior of Some Amino Acids in Water at 298.15 K: A Compressibility Approach

Apparent molar adiabatic compressibility, K 2,φ,S, of glycine, DL-α-alanine, DL-α-amino-n-butyric acid, L-leucine and L-phenylalanine in water and in (0.5, 1.0, 2.0, 4.0, 5.5 mol kg−1) aqueous sodium acetate and in (0.5, 1.0, 1.5, 2.0 mol kg−1) aqueous magnesium acetate solutions has been determined from sound velocity, u, measurements at 298.15 K. The partial molar adiabatic compressibilities at infinite dilution, K 0 2,S, obtained from K 2,φ,S data have been used to calculate the corresponding partial molar adiabatic compressibilities of transfer at infinite dilution, Δt K 0 2,S, from water to aqueous sodium acetate and magnesium acetate (cosolutes) solutions. The Δt K 0 2,S values are positive for the studied amino acids in case of both the cosolutes and the values increase with the increase of the concentrations of both the cosolutes. The trends of Δt K 0 2,S have been rationalized in terms of the hydration of hydrophilic and hydrophobic parts of the amino acids studied. The interaction coefficients and hydration number, n H, have also been calculated and are discussed in terms of the dehydration effect of sodium acetate and magnesium acetate upon the amino acids in solutions. Attempt has been made to correlate these results with the earlier reported volumetric and viscometric studies for the same systems.

Propensity for the Air/Water Interface and Ion Pairing in Magnesium Acetate vs Magnesium Nitrate Solutions: Molecular Dynamics Simulations and Surface Tension Measurements

Molecular dynamics simulations in slab geometry and surface tension measurements were performed for aqueous solutions of magnesium acetate and magnesium nitrate at various concentrations. The simulations reveal a strong affinity of acetate anions for the surface, while nitrate exhibits only a very weak surface propensity, and magnesium is per se strongly repelled from the air/water interface. CH3COO- also exhibits a much stronger tendency than NO3- for ion pairing with Mg2+ in the bulk and particularly in the interfacial layer. The different interfacial behavior of the two anions is reflected by the opposite concentration dependence (beyond 0.5 M) of surface tension of the corresponding magnesium salts. Measurements, supported by simulations, show that the surface tension of Mg(NO3)2(aq) increases with concentration as for other inorganic salts. However, in the case of Mg(OAc)2(aq) the surface tension isotherm exhibits a turnover around 0.5 M, after which it starts to decrease, indicating a positive net solute excess in the interfacial layer at higher concentrations.

Raman study of complexation in aqueous solutions of magnesium acetate

Raman spectra of aqueous solutions of magnesium acetate at 293 K have been studied in the concentration range 0.65–3.24 M, as have the Raman spectra of the crystallohydrate Mg(CH 3COO) 2·4H 2O. Fourier deconvolution and band fitting techniques have been used to analyse the spectra in three characteristic regions. The gradual evolution of two new components, in addition to the component corresponding to the CC vibration of the free acetate ion, is observed in the CC region of the solutions. These are identified as belonging to mono- and bisacetato complexes. In saturated solutions the bisacetato complexes are the dominating metal-ligand species. Their presence is confirmed also by Fourier deconvolution of the in-plane rocking CO 2 vibration.

Vibrational spectral studies of solutions at elevated temperatures and pressures. 12. Magnesium acetate

Raman spectra of aqueous solutions of magnesium acetate at temperatures from 25 to 250°C and at a pressure of 9 MPa have been studied to determine the cumulative formation constants for magnesium acetate complexes. The spectra obtained were analysed using bandfitting techniques, the Gauss-Z least squares method, and Factor Analysis with Equilibrium Constraints (FAEC). The results of this study suggest the presence of two complexes, [Mg(H 2O) 5OAc] + and [Mg(H 2O) 4(OAc) 2](where OAc − refers to CH 3COO −), at 25, 50, 100, and 150°C. The existence of a third complex [Mg(H 2O) 3(OAc) 3] − is also suggested at 150°C. Average enthalpies of formation were estimated as 9.0 ± 1.2 kJ mol −1 for the 1:1 complex and 17.0 ± 1.2 kJ mol −1 for the 1:2 complex.