Saturation Molalities and Standard Molar Enthalpies of Solution of Adenosine (cr), Guanosine. 2H2O(cr), inosine(cr), and Xanthosine. 2H2O(cr) in H2(l)

Published

October 1, 2003

Author(s)

Yadu D. Tewari, R Klein, Mark D. Vaudin, Robert N. Goldberg

Abstract

Saturation molalities m(sat) in H₂O(l) have been measured for the substances adenosine(cr), guanosine 2H₂O(cr), inosine(cr), and xanthosine 2H₂O(cr) over the temperature range T = 287.91 K to T = 308.18 K by using h.p.l.c.. The indicated states of hydration of these substances were established by performing Karl Fischer analyses of samples of these substances which had been equilibrated over H₂O(l) and of samples obtained by passing air over the wet crystals (air dried samples). The crystalline phases of these substances were identified by comparison of the results of x-ray diffraction measurements with results from the literature. Molar enthalpies of solution {Δ}_solH_m for adenosine(cr) and inosine(cr) were measured by using an isoperibol solution calorimeter. A stacking or self-association model was used to estimate values of the activity coefficients γ and relative apparent molar enthalpies L_{symbol} for these substances. These γ and L_{symbol} values were used to adjust the measured values of m(sat) and {Δ}_solH_m to the standard state and obtain values of the standard molar Gibbs free energy and enthalpy changes {Δ}_solG _m and {Δ}_solH _m, respectively, for the dissolution reactions of these substances. Values of {Δ}_solH _m calculated from the temperature dependence of values of {Δ}_solG _m were in good agreement with the values of {Δ}_solH _m obtained by using calorimetry.

Citation

Journal of Chemical Thermodynamics

Volume

35

Issue

10

Pub Type

Journals

Keywords

adenosine, calorimetry, enthalpy, entropy, Gibbs free energy guanosine, inosine saturation molality, xanthosine

Citation

Tewari, Y. , Klein, R. , Vaudin, M. and Goldberg, R. (2003), Saturation Molalities and Standard Molar Enthalpies of Solution of Adenosine (cr), Guanosine. 2H₂O(cr), inosine(cr), and Xanthosine. 2H₂O(cr) in H₂(l), Journal of Chemical Thermodynamics (Accessed September 14, 2024)