Molecular Modeling and Simulation: Force Field Development, Evaporation Processes and Thermophysical Properties of Mixtures

To gain physical insight into the behavior of fluids on a microscopic level as well as to broaden the data base for thermophysical properties especially for mixtures, molecular modeling and simulation is utilized in this work. Various methods and applications are discussed, including a procedure for the development of new force field models. The evaporation of liquid nitrogen into a supercritical hydrogen atmosphere is presented as an example for large scale molecular dynamics simulation. System-size dependence and scaling behavior are discussed in the context of Kirkwood-Buff integration. Further, results for thermophysical mixture properties are presented, i.e. the Henry’s law constant of aqueous systems and diffusion coefficients of a ternary mixture

An Inexpensive and Easily Constructed Device for Quantitative Conductivity Experiments

The low cost and easily replaced electrodes make this system practical for use in a general chemistry lab, while its accuracy and wide applicability permit its use in physical or quantitative chemistry experiments

An Inexpensive and Easily Constructed Device for Quantitative Conductivity Experiments

The low cost and easily replaced electrodes make this system practical for use in a general chemistry lab, while its accuracy and wide applicability permit its use in physical or quantitative chemistry experiments

Solubility of Gases in Liquids. XVI. Henry\u27s Law Coefficients for Nitrogen in Water at 5 to 50°C

The solubility of nitrogen in pure liquid water was measured in the pressure range 45 to 115 kPa and in the temperature range 5 to 50°C. These data are used to obtain Henry coefficients H 2,1 (T,P s,1 ) at the vapor pressure P s,1 of water. The temperature dependence of H 2,1 (T,P s,1 ) is accounted for by both a Clarke-Glew (CG) type fitting equation, and a power series in T−1, as suggested by Benson and Krause (BK). The imprecision of our measurements is characterized by an average deviation of ±0.038% from a four-term CG equation, and by an average deviation of ±0.042% from a three-term BK equation. From the temperature variation of H 2,1 (T,P s,1 ) partial molar quantities referring to the solution process, such as enthalpies and heat capacities of solution, are obtained. They are given in tabular form, together with H 2,1 (T,P s,1 ) and derived Ostwald coefficients L∞, at rounded temperatures. Finally, experimental results are compared with values calculated via scaled particle theory

Solubility of Gases in Liquids. 15. High-Precision Determination of Henry Coefficients for Carbon Monoxide in Liquid Water at 278 to 323 K

The solubility of carbon monoxide in pure liquid water was measured in the pressure range 60 to 110 kPa and the temperature range 278 to 323 K with a high-precision apparatus of the Benson-Krause type. These data are used to derive Henry coefficients H2, 1(T, Ps, 1), the temperature dependence of which is accounted for by both a Clarke-Glew type fitting equation and a power series in T−1. The imprecision of our measurements is characterized by an average deviation of H2, 1(T, Ps, 1) from these smoothing equations of about ±0.04%. From the temperature variation of H2, 1(T, Ps, 1) the partial molar quantities pertaining to the solution process (such as standard changes in enthalpy and heat capacity) are obtained. In addition, Ostwald coefficients are given in tabular form at rounded temperatures. Experimental results are compared with values calculated via scaled particle theory

Solubility of Gases in Liquids. 22. High­precision Determination of Henry Constants for Oxygen in Liquid Water from T = 274 to 328 K

The solubility of oxygen in pure liquid water was measured at a total pressure of about 100 kPa and from about T = 274.15 K to T = 328.14 K using an analytical method characterized by a precision of ± 0.05 per cent or less. From the experimental results, Henry’s law constants H2,1(T, ps,1) at the vapor pressureps,1 (T) of water as well as the Ostwald coefficientsL2,1∞ at infinite dilution were obtained via a rigorous thermodynamic method. Measurements were made at roughly 0.5 K intervals around T = 277.15 K, that is, around the temperature of the maximum density of water, between T = 274.15 K andT = 281.14 K (region I), and at roughly 5 K intervals aboveT = 283.17 K (region II). For each region, the data ln{H2,1 (T, ps,1) / Pa } were fitted to a three-term power series in 1 / T: the average percentage deviation of the experimental Henry’s law constants in region I is 0.013, while for region II 0.051 is obtained. The average percentage deviation of the entire set of measured Henry’s law constants (32 points), extending from T = 274.15 K toT = 328.14 K, is 0.039. Similar results are obtained for the Ostwald coefficients. Subsequently, the partial molar enthalpy changes on solution and the partial molar heat capacity changes on solution were obtained from the temperature dependence of the Henry’s law constant (van’t Hoff analysis). Agreement with calorimetrically determined quantities is excellent. We believe that our new values for the Henry’s law constantH2,1 (T, ps,1) and the Ostwald coefficientL2,1∞ of oxygen in water are the most reliable ones to date