Bhajan S. Lark

Partial Molar Volumes of Transfer of Some Amino Acids from Water to Aqueous Glycerol Solutions at 25°C

Apparent molar volumes of glycine, DL-α-alanine, L-valine, L-leucine, and L-phenylalanine in 0.5, 1.0, 2.0, 3.5, and 5.0 mB (mol-kg−1) aqueous solutions of glycerol have been obtained from solution densities at 25°C using precise vibrating-tube digital densimeter. The estimated partial molar volumes at infinite dilution Vo2 have been used to obtain the corresponding transfer volumes ΔtrV2o from water to different glycerol–water mixtures. The transfer volumes are positive for glycine and DL-α-alanine, and both positive and negative for the other amino acids over the concentration range studied. Interaction coefficients have been obtained from McMillan–Mayer approach and the data have been interpreted in terms of solute–cosolute interactions.

Ternary heat effects in ternary mixtures

Abstract Excess enthalpies of three ternary mixtures consisting of benzene + carbon tetrachloride + cyclohexane at 303.15 K, acetone + carbon tetrachloride + cyclohexane, and acetone + cyclohexane + chloroform at 298.15 K have been measured over the whole composition range using an adiabatic calorimeter. Ternary effects determined as the differences of the experimental excess heats from those of the sum of the binary contributions by the Nissema method are found to be positive for the first two systems and both positive and negative for the last system.

Excess volumes of propionic acid + cyclohexane, +benzene, +tetrachloromethane, +toluene, and +methanol

Abstract Excess volumes of propionic acid+cyclohexane, +benzene, +tetrachloromethane, +toluene, and +methanol are reported at 298.15 K. The results are explained in terms of the associative behaviour of the acid molecules, dipole-induced-dipole interactions, and preferred hydrogen bonding between acid and methanol molecules.