Browsing by Author "Barton, Allan F. M."

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Dissolution Rates of Ionic Solids: Part 2.—Calcium Bisfdihydrogen phosphate) Monohydrate+Anhydrite (Calcium Sulphate)
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (12), 1974) Barton, Allan F. M.; McConnel, Stephen R.
The dissolution rate of commercial superphosphate fertiliser was studied at 25, 35 and 45°C using a rotating disc of the solid material. The kinetics were followed by means of a calcium ion-selective electrode and spectrophotometric analyses. The initial process was observed to consist predominately of calcium bis(dihydrogen phosphate) monohydrate dissolution and was transport controlled with an apparent activation energy of 13 ± 3 kJ mol–1. Thereafter diffusion of dissolved monocalcium bis(dihydrogen phosphate) monohydrate through a porous layer of increasing thickness determined the rate of dissolution.
p-V-T Studies on Molten Alkali Nitrates: Part 1.—Thermal Pressure Coefficients and Compressibilities
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (1), 1978) Bannard, John E.; Barton, Allan F. M.
The p-V-T relationships of the molten alkali nitrates (Li, Na, K, Rb and Cs) were determined using a gas-pressurised, externally-heated pressure vessel. The cells were the pyknometer type with a long capillary barrier between the pressurising gas and the bulk of the liquid. Data, over a range of temperature from 500 to 800 K and a range of pressure to 1400 bar, were plotted in the form of isochores and used to determine densities and compressibilities of the liquids.
Simultaneous Conductance and Volume Measurements on Molten Salts at High Pressure
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Barton, Allan F. M.; Speedy, Robin J.
A simple method is described which allows the simultaneous measurement of the conductance and volume of ionically conducting liquids at high pressure. Precise and extensive (90 to 220°C, 10 to 2000 bar) pressure, temperature, volume and conductance data are presented for the salts R4N+BF (where R is n-butyl to n-heptyl). None of the existing theories which predict the temperature and volume dependence of transport in liquids is consistent with the results. A simple model is developed which quantifies the notion of structure in liquids in terms of a distribution of coordination number, as suggested by Bernal.1 The postulate that transport is related to the incidence of uncoordinated molecules, N0, and the calculation of N0 in terms of the partition function for the model allow general relations to be established between the temperature and volume dependence of transport and the thermodynamic properties of the liquid, which account in a comprehensive qualitative way for the trends observed in real liquids. A further development of the model accounts quantitatively for the temperature and volume dependence of the molar conductivity of the series of molten salts. These results support the basic physical postulates of the model, that the temperature and volume dependence of transport in liquids are related to the frequency of the local fluctuations in structure as indicated by the incidence of uncoordinated molecules.