John Walkley

Entropy of volume expansion of gases dissolved in non-polar solvents

The partial molal volumes of six gases dissolved in four non-polar solvents have been measured. The values are compared to those of earlier workers. An attempt is made to assess the consistency of the data using the regular solution theory “entropy of volume expansion” concept.

Single‐Particle Theory for Systems at High Densities. I. Characteristic Reduction Parameters for the Mie—Lennard‐Jones Pair Interaction Potential from Zero‐Point Crystal Data

The energy and length reduction parameters for a 12:6 pair‐potential are characterized from the consideration of zero‐point crystal data. The crystal is considered to be represented by a single‐particle anharmonic Einstein model. This anharmonic potential is considered to be spherically symmetric and is developed according to the cell theory of Lennard‐Jones and Devonshire. No further approximations to the form of this potential are required in the evaluation of the energy eigenvalues from the wave equation. Both the Wentzel—Kramers—Brillouin approximation and a more exact finite difference method of evaluating the energy eigenvalues are discussed. The systems examined are argon, neon, deuterium, hydrogen, and helium.

Quantum Cell Model. I. The Uniform Potential Approximation

The equation of state and related thermodynamic properties are calculated for a uniform potential approximation to the Lennard‐Jones cell theory model employing quantum statistical mechanics. The simple form of the cell potential for this model allows the energy eigenvalues to be readily computed. A comparison to the available experimental compressibility data for hydrogen and deuterium is made.

Studies in regular solution theory. Part 1.—Solubolity studies of tetraphenyltin in simple non-polar solvents

The solubility of tetraphenyltin in a number of non-polar solvents is presented. The data are analyzed in terms of Hildebrands theory of regular solutions. The large molar volume of this solute requires the inclusion of a Flory-Huggins term in the saturation solubility equation. The possible limitation of the interaction-energy geometric-mean rule are examined and a comparison is made with data for the solubility of stannic iodide, iodine and sulphur in a similar set of solvents.

Quantum Cell Model Equation of State

A quantum‐mechanical cell model equation of state is developed using the Wentzel—Kramers—Brillouin approximation to solve the Schrodinger wave equation. Compressibility data for hydrogen, deuterium, and helium is obtained for a Lennard‐Jones 12–6 potential, over a wide range of temperature and density. A comparison with experiment shows the expected good agreement in the solid state, the agreement becoming progressively worse for the liquid and gas phases.

Single‐Particle Theory for Systems at High Densities. II. Solid Argon and Argon—Quinol Clathrate

A quantal version of the Lennard‐Jones and Devonshire cell theory is used to predict the thermodynamic properties of solid argon and argon in a β‐quinol matrix at low temperatures. The agreement with the experimental properties of solid argon is very good and an interpretation of the specific heat contribution due to cavity formation is discussed. The comparison with the argon—quinol clathrate data is not good. Reasons for this discrepancy are discussed and krypton— and methane—quinol clathrates are examined.

Single‐Particle Theory for Systems at High Densities. III. Solid Neon and Some Considerations of the Second Virial Coefficient

A quantal version of the Lennard‐Jones and Devonshire cell model is used to predict the thermodynamic properties of solid neon. As was observed previously for solid argon, good agreement with experiment is obtained if the parameters of the assumed 12:6 pair‐potential are calculated from zero‐point crystal data. In view of the success of the application of this theory to the solid state, second virial coefficient data are interpreted using the zero‐point reduction parameters. Again a satisfactory comparison of experiment and theory is observed.

Reduction Parameters for an Unspecified Intermolecular Potential. A Harmonic‐Oscillator Approximation

The reduction parameters for an unspecified pair interaction potential have been calculated for argon and krypton. The method used is a sphericalized equivalent of the method first proposed by Corner. It is similarly limited, but only in the present harmonic version, to systems for which the zero‐point energy is very small. The parameters obtained from solid‐state data allow an extremely accurate corresponding states comparison of second virial coefficient data. Third virial and also viscosity data similarly appear to be reduced to single classical curves. This suggests that any nonadditivity of potential present in the multiparticle‐interaction situation of the solid phase must be very small.

Thermodynamic solubility: properties of gas mixtures. Part 1.—Two component gas mixtures in water at 25°C

The saturation solubility of O2+ CH4, O2+ N2 and N2+ CH4 mixtures in water at 25.00°C and 1 atm total pressure are reported at O2 partial pressures of 0.25, 0.5 and 0.75 atm. The solubility of oxygen at a partial pressure of 0.5 atm in the presence of 0.5 atm pressure of helium, of ethane and of krypton are also reported. In all case the saturation solubility of each gas is reduced below the expected Henrys Law value. Current theories for the solubility of gases in water are discussed.

QUANTUM CELL MODEL. II. A CORRESPONDING-STATES APPROACH TO AN EQUATION OF STATE AT HIGH DENSITIES

The equation of state of a system of light molecules is regarded as the sum of a classical term and a quantum correction term. Experimental data for argon are used as the classical contribution and the quantum term is evaluated both for a 12–6 Lennard‐Jones cell model and for a uniform potential approximation of this model. The former is seen to give a quantum correction term far too small in magnitude, while the latter approximation produces theoretical isotherms in good agreement with experimental data for both hydrogen and deuterium. Experimental hydrogen—deuterium data are then used to construct high‐temperature classical corresponding‐states isotherms.