A.C.G. van Genderen

The heat capacity and derived thermodynamic functions of La2Zr2O7 and Ce2Zr2O7 from 4 to 1000 k

Abstract The heat capacities of cerium and lanthanum zirconate (Ce 2 Zr 2 O 7 and La 2 Zr 2 O 7 ) were measured from 4 to 400K by adiabatic calorimetry. The derived thermodynamic functions, H °, S ° and {G ° − H °(0)} T were calculated. The standard molar entropies at 298.15K were determined as 230.21 ± 0.46 J/mol · K and 238.53 ± 0.48 J/mol · K. Enthalpy increments relative to 298.15 K were measured by drop calorimetry from 500 to 900 K. From these data the thermodynamic functions, including the enthalpy and Gibbs free energy of formation of the two compounds were derived for temperatures up to 1000 K.

A thermodynamic method for the derivation of the solidus and liquidus curves from a set of experimental liquidus points

A thermodynamic method is presented which makes possible the correct derivation of solidus and liquidus curves from a set of experimental liquidus points. In an iterative procedure, which is based on the equal-G curve and which uses intermediate phase diagram calculations, the liquidus of the calculated phase diagram is made to run through the experimental liquidus points. In addition, information about the thermodynamic mixing properties of the system is obtained. Results are given for the system p-dichlorobenzene + p-dibromobenzene, K2CO3 + K2SO4, KCl + NaCl.

Properties of mixed crystalline organic material prepared by zone levelling II. Vapour pressures and excess Gibbs energies of (p-dichlorobenzene + p-dibromobenzene)

Abstract Vapour pressures of two kinds of solid mixtures of ( p -dichlorobenzene + p -dibromobenzene): (a), homogeneous mixed crystals prepared by zone levelling and (b), solid material obtained by quenching, were measured between 273 and 293 K by a static method. Samples of quenched material showed considerably higher vapour pressures than samples of homogeneous material. When translated into excess Gibbs energies, the results from quenched material yield values that exceed the values obtained for zone-levelled material, e.g. for the 1—1 mixture by about 150 J mol −1 .

Binary common-ion alkali halide mixtures; a uniform description of the liquid and solid state

Abstract Empirical relations for the thermodynamic excess behaviour of binary common-ion alkali halide mixtures were derived. For the liquid state this gave rise to G E(1) ( x , T g ) = 0.68 H E(1) ( x , T g ) and S E(1) ( x , T g )=0.32 H E(1) ( x , T g )/ T g , and for the solid state G E(1) ( x , T )= A (1− T / (2565 K)) x (1− x )(1+ B (1−2 x )), in which the A parameter can be calculated from relative differences in unit cell volumes of the pure solid components A calc (kJ mol −1 ) = 11.53(Δ V / V s )+ 89.40(Δ V / V s ) 2 and the B parameter which is a measure for the asymmetry can be calculated from the A parameter using B = 1.04 × 10 −2 ( A calc /kJ mol −1 ). The phase diagrams were calculated and compared with experimental phase diagram data for twenty binary common-ion alkali halide systems that show complete sub-solidus miscibility.

The heat capacity and derived thermodynamic functions of La2Si2O7 and Ce2Si2O7 from 4 to 1000 K

Abstract The heat capacities of cerium and lanthanum silicates (Ce2Si2O7 and La2Si2O7) were measured from 4 to 400 K by adiabatic calorimetry. The derived thermodynamic functions, {Ho(T) − Ho(0)}, So and {Go− Ho(0)}/T were calculated. The standard molar entropies at 298.15 K were determined as 220.32 ± 0.44 J mol−1 K−1 and 210.7 ± 0.42 J mol−1 K−1, respectively. Enthalpy increments relative to 298.15 K were measured by drop calorimetry from 500 to 900 K. From these data the thermodynamic functions, including the enthalpy and Gibbs free energy of formation of the two compounds were derived for temperatures up to 1000 K.