Standard molar entropy

About: Standard molar entropy is a research topic. Over the lifetime, 1586 publications have been published within this topic receiving 29886 citations.

In‐situ microcalorimetry study on thermodynamic functions of Cu 2 O nanocubes

Abstract: Four different sizes of cuprous oxides (Cu2O) nanocubes in the range of 40–120 nm were synthesised by liquid phase reduction method. The morphology, size, and structure of synthesised Cu2O nanocubes were characterised by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In-situ microcalorimetry was used to calculate the conventional and surface thermodynamic functions of Cu2O nanocubes by combining thermodynamic principles and transition state theory. The effect of particle size on conventional thermodynamic functions and surface thermodynamic functions were investigated and analysed, whose results were supported by the established thermodynamic models. Results showed that both the standard molar enthalpy of formation and the standard molar entropy of formation were increased with decreasing particle size, while the standard molar Gibbs energy of formation decreased. Also, the molar surface Gibbs energy, molar surface enthalpy, and molar surface entropy grew with the reduction of particle size, which correlated well with the models. Such a property is of scientific significance for enriching and developing disciplines such as surface physics and surface thermodynamics.

The thermodynamic properties of star-shaped fullerene-containing poly-N-vinylpyrrolidone

Abstract: The temperature dependence of the heat capacity of star-shaped fullerene-containing poly-N-vinylpyrrolidone was studied over the temperature range 6–390 K by precision adiabatic vacuum and dynamic scanning calorimetry. The temperature intervals and thermodynamic characteristics of phase transitions were determined. The low-temperature dependence of the heat capacity of the substance was analyzed according to the Debye theory of the heat capacity of solids and its multifractal generalization. The data obtained were used to calculate the standard thermodynamic functions C p o (T),H o(T)-H o(0), S o(T), and G o(T)-H o(0) of fullerene-containing poly-N-vinylpyrrolidone from T → 0 to 390 K. The standard entropy of formation of the polymer from simple substances and the entropy of its synthesis from poly-N-vinylpyrrolidone and fullerite C60 at 298.15 K were calculated. The thermodynamic characteristics of fullerene-containing poly-N-vinylpyrrolidone are compared with those of the polymer-analogue without C60.

The thermodynamic properties of tetraallylsilane from T → 0 to 335 K

Abstract: The temperature dependence of the heat capacity of tetraallylsilane in the crystalline, supercooled liquid, and liquid states was studied in an adiabatic vacuum calorimeter in the temperature range 7-335 K. The temperature and enthalpy of its fusion and the first and second cryoscopic constants were determined. The experimental data were used to calculate the C° p , H°(T)-H°(0), S°(T), and G°(T)-H°(0) thermodynamic functions of tetraallylsilane in the temperature range from T → 0 to 335 K and the standard entropy of formation at 298.15 K. The isochoric heat capacity and its lattice and atomic components were estimated.

The Thermodynamic Properties of Magnesium Uranoborate

Abstract: The standard enthalpy of formation of crystalline Mg(BUO5)2 at 298.15 K (−4347.5 ± 8.0 kJ/mol) was determined by reaction calorimetry. The heat capacity of magnesium uranoborate was studied by adiabatic vacuum calorimetry over the temperature range 8–330 K. The thermodynamic functions of the compound were calculated. The standard entropy and Gibbs energy of formation at 298.15 K were found to be −903.0 ± 2.1 J/(mol K) and −4078.5 ± 9.0 kJ/mol, respectively.