Thermodynamic Properties of A.nilotica var. nilotica and A.seyal var. seyal Gums Solutions

The thermodynamic properties of A.nilotica gum, A. seyal gum solutions were measured and calculated. The partial specific volume of gum, partial specific volume of the solvent (water) and the volume fractions were measured and calculated. Thermodynamic studies involved the estimation the partial specific volume of gum, partial specific volume of the solvent (water) and solute (gum) and the volume fraction of water (φ1 ) and that of gums (φ2 ) in gums solutions of different concentrations. For composite samples of A.nilotica var. nilotica and A.seyal var. seyal average were found to be 0.999 cm3 g -1 and 0.618 cm3 g -1 , 0.998 cm3 g -1 and 0.643 cm3 g -1 respectively. The results show that the sequences of the specific volumes of the gums under studies are in the order of decreasing molecular weight of these gums. Second virial coefficient (A2 ) average for composite samples of A.nilotica var.nilotica were found to be 0.97×10-3 , Where as for composite samples of A.seyal var.seyal was found to be 2.09×10-3 ,The results explained that water is good solvent for the tow types of gums .Chemical potential range have been calculated from osmotic measurement for different concentrations and was found to be –1.997×10-3 to -8.790×10-3 joule g-1 on average for composite samples of A.nilotica var.nilotica. For composite samples of A.seyal var.seyal the average it was found to be -1.1576×10-4 to -4.1382×10-4 joule g -1 , The results show that the change in chemical potential of water in A.seyal var.seyal gum solution was greater than the change in chemical potential of water in A.nilotica var.nilotica gum solution. Free energy of mixing range of composite samples of A.nilotica var. nilotica average was found to be (-1.2768×10-3 to -3.1773×10-3 ). For composite samples of A.seyal var.seyal average was found to be (-1.6925×10-3 to - 5.7145×10-3 ).The obtained results indicate that A.seyal gum thermodynamically resembles A.nilotica gum and they were interacting with water more than A.nilotica gum.