Thermochemical Properties of Dissolution of Nicotinic Acid C6H5NO2(s) in Aqueous Solution

Autor: Dan Xu, Chun-Sheng Zhou, Yu-Xia Kong, You-Ying Di
Rok vydání: 2017
Předmět:
Zdroj: Journal of Solution Chemistry. 46:886-895
ISSN: 1572-8927
0095-9782
Popis: Nicotinic acid (also known as niacin) was recrystallized from anhydrous ethanol. X-ray crystallography was applied to characterize its crystal structure. The crystal belongs to the monoclinic system, space group P2(1)/c. The crystal cell parameters are a = 0.71401(4) nm, b = 1.16195(7) nm, c = 0.71974(6) nm, α = 90°, β = 113.514(3)°, γ = 90° and Z = 4. Molar enthalpies of dissolution of the compound, at different molalities m/(mol·kg−1) were measured with an isoperibol solution–reaction calorimeter at T = 298.15 K. The molar enthalpy of solution at infinite dilution was calculated, according to Pitzer’s electrolyte solution model and found to be $$ \Delta_{\text{sol}} H_{m}^{\infty } = ( 2 7. 3 \pm 0. 2) $$ kJ·mol−1 and Pitzer’s parameters ( $$ \beta_{{\text{MX}}}^{{\text{(0)}L}} $$ , $$ \beta_{{\text{MX}}}^{{\text{(1)}L}} $$ and $$ C_{{\text{MX}}}^{\phi L} $$ ) were obtained. The values of apparent relative molar enthalpies ( $$ {}^{\phi }L $$ ) and relative partial molar enthalpies ( $$ \overline{{L_{2} }} $$ and $$ \overline{{L_{1} }} $$ ) of the solute and the solvent at different molalities were derived from the experimental enthalpy of dissolution values of the compound. Also, the standard molar enthalpy of formation of the anion $$ {\text{C}}_{ 6} {\text{H}}_{ 4} \text{NO}_{2}^{-} $$ in aqueous solution was calculated to be $$ {\Delta_{\text{f}}^{} H}_{\text{m}}^{\text{o}} ({\text{C}}_{ 6} {\text{H}}_{ 4} {\text{NO}}_{2}^{-} \text{,aq}) = - \left( {603.2 \pm 1.2} \right)\;{\text{kJ}}{\cdot}{\text{mol}}^{-1} $$ .
Databáze: OpenAIRE
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