Browsing by Author "Spong, A H"

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    Electrolytic conductances and related properties of solutions of some acids and salts in acetone
    (1966) Brookes, Hugh Clive; Spong, A H
    Although a thorough investigation of various methods of preparing pure, anhydrous acetone has been made (cf. Sadie), no investigations of methods for determining the moisture content of this solvent have previously been described. A solvent with a consistently low water content is essential for electrochemical measurements. Accordingly an extensive study of moisture content determination in acetone-was made. A modified Karl Fischer titration procedure was found to be most suitable for the very low moisture contents of the acetone used in this work. All A.C. conductance measurements made using two platinised electrodes are, in some degree, liable to errors due to polarization, end effects and the state of the electrode surfaces. Several workers have also found errors due to the presence of finely divided platinum, such as adsorption of electrolyte on the colloidal platinum, the shaking effect and catalysis of reactions in solution. These errors are reduced by using lightly platinised or bright platinum electrodes, but polished electrodes give rise to increased polarization errors. In this work conductance measurements were made using a new four-electrode A.C. potentiometer, which employs bright platinum electrodes enabling conductance measurements to be carried out in acetone without recourse to platinisation, thus avoiding errors due to the presence of platinum black, contact resistances of electrodes and the like. The measurements on this apparatus were shown to be independent of frequency using aqueous potassium chloride solutions, and the accuracy of the results was tested using aqueous sodium chloride solutions. Perchlorates have been considered by some investigators (e.g. Ross Kane) to be strong electrolytes in acetone solutions and other workers (e.g. Accascina and Schiavo) found the alkali perchlorates to be weak electrolytes. The approximate limiting ionic conductances calculated by these last named workers were at variance with those of other investigators (e.g. Kraus). It therefore appeared that a study of the conductances of solutions in acetone of perchloric acid and some of its salts by the new potentiometric method would be advantageous. The conductances of three alkali perchlorates and the previou3ly unknown conductances in acetone of ammonium perchloratey pure anhydrous perchloric acid and lithium chloride were measured by the potentiometric method. Limiting equivalent conductances and dissociation constants were calculated for all the electrolytes and the results discussed. These electrolytes were, in general, found to be relatively weak in acetone, although perchloric acid is considerably stronger than hydrochloric acid. The conductance results indicated that the potentiometric method should be generally applicable to electrolyte solutions in all solvents, and can be used to advantage in all cases influenced by the errors previously mentioned. It is generally recognized that interpretation of conductance data and the development of the theory of electrolyte solutions is seriously hindered by the lack of transport data in non-aqueous solvents. Transference measurements were undertaken using a conductimetric moving boundary method, and a limiting transport number for the anion constituent of potassium thiocyanate was obtained in acetone. This is the first reasonably accurate limiting transport number to have been measured in acetone. From the equivalent conductance data of this work, and the literature, the first limiting ionic conductances in acetone have been calculated and the results discussed. The limiting conductance of the hydrogen ion 101cm² ohm-¹ equiv-¹ , was not found to be anomalous, as for example, in water. Anions were found to have generally higher conductances than cations, which is consistent with the view that cations are in general, more solvated than anions in dipolar aprotic solvents. Conductance results of numerous workers have indicated considerable uncertainty about the entities present in acetone solutions of hydrogen chloride. In order to add to existing knowledge, tracer diffusion coefficients of hydrogen chloride in acetone solutions were measured at 15⁰ , 25⁰ and 35⁰C over a range of concentrations using hydrogen chloride labelled with chlorine -36. The capillary tube method was used, and concentrations were measured by a scintillation counting procedure. Complete interpretation of the results is impossible in the light of present knowledge, but they appear to be consistent with suggestions, based on conductance measurements in this system, that hydrogen chloride polymers may be present.
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    Physico-chemical studies of solutions of some acids in acetone
    (1964) Sadie, Francois Gustaves du Bois; Spong, A H; Hotz, M C B
    The work of Hotz showed the lack of knowledge of the behaviour of electrolytes in acetone solutions as well as the uncertainty as to the possibility of preparing anhydrous acetone and the stability of this solvent, if it could be prepared. An extensive study was therefore undertaken in which the efficiency of various desiccants was studied in producing acetone as anhydrous as could be obtained. A very efficient still was designed and the average water content of the acetone produced was of the order of 0.006 per cent which is much lower than reported by any previous investigator. Moisture determinations were done using a modified Karl Fischer reagent.
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    Studies in the gas chromatography of ammonia, with special reference to packings containing solutions of silver salts in some organic solvents
    (1960) Du Plessis, Louis Armand; Spong, A H
    It has been found that the gas chromatography of ammonia on certain fixed phases containing salts yields chromatograms consisting of a peak followed by a plateau or a succession of plateaux of progressively decreasing height. Such chromatograms have been interpreted in terms of ammine formation in the column and methods have been theoretically elaborated for using measurements on the chromatograms to find the dissociation pressures of the ammines and the ratios of ammonia taken up to silver in the fixed phase. These methods require the calibration of the detector, so that ammonia partial pressures can be found from chromatogram heights, and this has been done by a chromatographic method. In most cases, the ratio of ammonia to silver in the fixed phase does not yield conclusive information on ammnine composition, because there is usually evidence that the salt is present in different forms or is only partially converted to ammine.
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    Studies in the gas chromatography of ammonia, with special reference to packings containing solutions of silver salts in some organic solvents
    (1959) Du Plessis, Louis Armand; Spong, A H
    It has been found that the gas chromatography of ammonia on certain fixed phases containing salts yields chromatograms consisting of a peak followed by a plateau or a succession of plateaux of progressively decreasing height. Such chromatograms have been interpreted in terms of ammine formation in the column and methods have been theoretically elaborated for using measurements on the chromatograms to find the dissociation pressures of the ammines and the ratios of ammonia taken up to silver in the fixed phase. These methods require the calibration of the detector, so that ammonia partial pressures can be found from chromatogram heights, and this has been done by a chromatographic method. In most cases, the ratio of ammonia to silver in the fixed phase does not yield conclusive information on ammnine composition, because there is usually evidence that the salt is present in different forms or is only partially converted to ammine.
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    A study of the self-diffusion of certain of the lower alkyl halides
    (1955) Stein, Louis Henry; Carman, P C; Spong, A H
    The self-diffusion coefficients of Mel, and Et-, nPris-,isoPr-, nBu-, isoBu- and secBu-iodides and bromides were determined by application of the capillary tube method and using iodine-131 and bromine-82 for labelling the compounds. Viscosities were measured for those compounds for which the data in the literature were insufficient for calculation of energies of activation. The diffusion coefficients were of the order of 2 x 10⁻⁵ cm².sec⁻ with activation energies of 2 kcal./mole; determined from plots of log D/T versus l/T. The temperatures at which coefficients were measured were 7.35, 19.35 and 30.00° C. The activation energies measured agreed with those for viscous flow as is required by the theories of Frenkel and Eyring.