The use of conductivity measurements in organic solvents for the characterisation of coordination compounds

A combined quantum mechanical (QM) and molecular mechanical (MM) potential has been developed for the study of reactions in condensed phases. For the quantum mechanical calculations semiempirical methods of the MNDO and AM1 type are used, while the molecular mechanics part is treated with the CHARMM force field. Specific prescriptions are given for the interactions between the QM and MM portions of the system; cases in which the QM and MM methodology is applied to parts of the same molecule or to different molecules are considered. The details of the method and a range of test calculations, including comparisons with ab initio and experimental results, are given. It is found that in many cases satisfactory results are obtained. However, there are limitations to this type of approach, some of which arise from the AM1 or MNDO methods themselves and others from the present QM/MM implementation. This suggests that it is important to test the applicability of the method to each particular case prior to its use. Possible areas of improvement in the methodology are discussed.

A combined quantum mechanical and molecular mechanical potential for molecular dynamics simulations

The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO3-CO2-H2O

Theoretical and experimental studies of multiple nucleation

Real surface area measurements in electrochemistry

Monolayer Formation in the Reduction of Nickel and Silver Ions from the LiCl ‐ KCl Eutectic

The adsorption of the hexafluorophosphate ion at the non-aqueous solution-mercury interface

Compact double layer as a function of temperature and pressure

THE hydrogen electrode is the primary standard to which all electrode potentials are referred and is used in cells without liquid junction for measurements of high accuracy. The potential of the hydrogen electrode is corrected to the standard pressure of one atmosphere on the basis that the electrode is in equilibrium with the measured partial pressure of hydrogen above the solution. It is, however, not the gas phase which directly determines the potential, but the hydrogen in solution ; and a tacit assumption that the concentration of dissolved hydrogen is unequivocally defined by the gas pressure is false. This error can arise in two ways.

The Hydrogen Electrode

lmpedances were measured of polarized platinum microelectrodes in the molten salt systems, LiCl-KCl at 400 deg C, 530 deg C. Frequency dispersion of both the observed resistance and capacitance was evident in all cases, but apparent double layer capacities obtained by extrapolation to infinite frequency were in reasonable accord with some previously reported data. They were of magnitudes consistent with a simple Helmholtz model although the anodic values tend to be high, perhaps because of specific adsorption. Some measurements of faradaic impedance were also made, but these were less successful and the exchange current for the Pt/Pt/sup 2+/ system was high. (auth)

http://jes.ecsdl.org/content/108/11/1013.full.pdf

Graham Hills

Papers

Monolayer Formation in the Reduction of Nickel and Silver Ions from the LiCl ‐ KCl Eutectic

The adsorption of the hexafluorophosphate ion at the non-aqueous solution-mercury interface

Compact double layer as a function of temperature and pressure

The Hydrogen Electrode

Impedance Phenomena in Molten Salts