Affiliation:
1. Laboratory of BiocyberneticsInstitute of Pathological Physiology, First Faculty of Medicine, Charles University
Abstract
When modeling body fluids using physical chemistry, we en-countered a contradiction. We proceeded from the erroneous assumption that the molar amount of water in an aqueous so-lution is the molar amount of H2O molecules (mass divided by the mass of one H2O
molecule). Thus, in one kilogram of pure water, we calculated 55.508 moles of water because the molar mass of H2O is 18.01528 g / mol. When calculating the molar fractions as the molar amount of the substance divided by the solution's total molar amount, we thus obtained numerically completely different values than for molalities or molarities. According to the theory, these values should be substitutable. However, it turned out that using these values in the calculati-ons of the solubility of gases in aqueous solutions showed us an error of about 55 mol/kg. Similar errors began to be reported for chemical processes with different numbers of reactants and products (at the same number, the error is annulled algebrai-cally). So is the water molality really about 55 mol/kg? No. This is because water forms bonds with each other, which cluster more H2O molecules into larger particles. From the required molar amount of water, we derived the dissociation constant and enthalpy of this bond. The results are compatible with data from the National Institute of Standards and Technology (NIST) and the data of formation energies of individual substances. Using these constants, it is possible to derive the molar amount of water in aqueous solutions and subsequently make calculati-ons over molar fractions, the results of which begin to coincide with the measured and published experiments.
Publisher
Creative Connections s.r.o.