Thermodynamic and Calorimetric Study of Acetylsalicylic Acid (Aspirin) and Ibuprofen

Enthalpies of solution and dilution of aqueous solutions of sodium acetylsalicylic acid salt and ibuprofen salt were measured with an isoperibolic calorimeter at 293.15 K, 298.15 K, 303.15 K, 308.15 K and 318.15 K. The concentration of the electrolyte was restricted to the solubility of the salt at various temperatures and did not exceed 0.035–0.057 mol kg-1, depending on the temperature studied. The Virial coefficients were derived from Pitzer's model and the excess thermodynamic functions of both the solution and the components of the solution were calculated. An analysis of the thermodynamic characteristics of the solution in terms of concentration and temperature interval was carried out and discussed. Additionally, an analysis was performed by differential scanning calorimetry (DSC)

Analysis of the response of thermal sensors in adsorption microcalorimetry

Three different designs for adsorption calorimeters are presented, which use sensors based on the Seebeck effect. The noises of signals with respect to the baseline are evaluated on each one of the builded equipment and the detection limit of the thermal effects is expressed in µWatt. It was determined that the different designs and working conditions affect the baseline noise and the detection limit. Values of the noise in the baseline are between ± 100 µV and ± 0,5 µV and between 887,2 and 24 µWatt. These values allow making measures in the solid-gas interphase with very good precision.Fil: García Cuello, Vanessa Silenia. Universidad de los Andes; ColombiaFil: Moreno Piraján, Juan Carlos. Universidad de los Andes; ColombiaFil: Giraldo Gutiérrez, Liliana. Universidad Nacional de Colombia; ColombiaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

Adsorption micro calorimeter : Design and electric calibration

In this work, it is described an innovative heat flux micro calorimeter Tian-Calvet type designed to measure adsorption heats and reactions as well as adsorption isotherms. It consists in an adsorption instrument for volumetric gases, which is coupled to the micro calorimeter. The changes in the pressure are monitored by means of high sensitivity and high precision pressure transducers. The micro calorimeter has thermo elements that work by a Seebeck effect, in a twin cells system. The cells are inside a box in which the temperature can be adjusted from 77 to 300 K. The sensitiveness of the calorimeter is established by applying a perfectly known electric work. The results corresponding to the electric calibration, the base line stability determination and the time constant in the equipment are shown.Fil: García Cuello, Vanessa Silenia. Universidad de Los Andes. Bogotá; ColombiaFil: Moreno Piraján, Juan Carlos. Universidad de Los Andes. Bogotá; ColombiaFil: Giraldo Gutiérrez, Liliana. Universidad Nacional de Colombia; ColombiaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Zgrablich, Giorgio. Universidad Nacional de San Luis; Argentin

Variation of the noise levels in the baseline of an adsorption microcalorimeter

This work shows the results obtained to determine the noise in the baseline of a specially designed Tian Calvet-Type adsorption microcalorimeter. The results show that noise levels vary from 0.5 to 10 μV, which were evaluated varying the electrical work and the micro calorimeter surrounding temperature. Relationships can be seen between the variables employed in the observation of stability, temperature, potency levels and generated noise. © 2009 Akadémiai Kiadó, Budapest, Hungary.Fil: García Cuello, Vanessa Silenia. Universidad de los Andes; ColombiaFil: Moreno Piraján, Juan Carlos. Universidad de los Andes; ColombiaFil: Giraldo Gutiérrez, L.. Universidad Nacional de Colombia. Sede Bogotá; ColombiaFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Grupo Vinculado Bionanotecnología y Sistemas Complejos | Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Grupo Vinculado Bionanotecnología y Sistemas Complejos. - Universidad Tecnológica Nacional. Facultad Regional San Rafael. Grupo Vinculado Bionanotecnología y Sistemas Complejos; ArgentinaFil: Zgrablich, Jorge Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Grupo Vinculado Bionanotecnología y Sistemas Complejos | Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Grupo Vinculado Bionanotecnología y Sistemas Complejos. - Universidad Tecnológica Nacional. Facultad Regional San Rafael. Grupo Vinculado Bionanotecnología y Sistemas Complejos; Argentin