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  • Author or Editor: N. Adhyapak x
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Abstract  

Theoretical activation energy of self-diffusion of zinc, chloride and chromate ions has been computed on the basis of the Onsager and Arrhenius equations. These values are compared with the experimentally determined ones for the self-diffusion of Zn2+ ions in the present work as well as previously reported values for self-diffusion of Cl and CrO 4 2– ions. A reasonably good agreement is observed between the two values.

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Abstract  

The values of activation energy required for the diffusion of ZnCl2 and for Cd2+ ions in Cd/Ac/2 are reported in agar gel medium at 5×10–5 and 0.001M concentration, respectively. These values are compared with the previously reported values in the same systems at different concentrations. The decrease in activation energy with concentration of electrolyte is in agreement with the Wang's model.

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Abstract  

The diffusion of cobalt sulphate is studied in 1% agar gel over a concentration range of 10–5 to 0.2M at 25 °C. The experimental values of the diffusion coefficient at various concentrations determined by the zone-diffusion technique are compared with the theoretical values of diffusion coefficinets computed on the basis of Onsager-Fuoss theory. The observed deviations are interpreted in terms of relative contributions of diffusion-enhancing and diffusion-retarding interactions occurring in the water-gel-electrolyte system.

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Abstract  

The activation energy for the diffusion of ZnSO4 as a function of electrolyte concentration is computed by least squares fitting of the diffusion coefficient data obtained at various temperatures in the Arrhenius equation. It is observed that the activation energy decreases with increasing concentration of the electrolyte. This observation is accounted for on the basis of Wang's model. Further, the obstruction effect caused by the agar macromolecules in the diffusion path of ZnSO4 uis also determined at these concentrations by varying the gel concentration at 25°C., The obstruction effect expressed in terms of a found to decrease with ZnSO4 concentration and explained on the basis of competitive hydration of diffusing ions and agar molecules.

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Abstract  

The obstruction effect and activation enerqy for the self-diffusion of Co2+ ions in CoSO4 have been computed using the zone-diffusion technique in agar gel medium at five different concentrations of the electrolyte. Both parameters are found to decrease with an increase in electrolyte concentration. The decrease in obstruction effect expressed in terms of is attributed to the competitive hydration between ions and agar molecules in a diffusion system while the decrease in activation energy is explained by considering the changes in the physical properties of the solution with concentration at microscopic level.

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Abstract  

Tracer-diffusion of Zn2+ ions in the presence of CoSO4 is studied at 25°C in 1% agar gel over a concentration range of 10–5 to 0.25M using a zone-diffusion technique. The deviations observed between experimental and theoretical values of diffusion coefficients are explained by considering different types of interactions occurring in the ion-gel-water system. Further, study of the obstruction, effect in the diffusion of Zn2+ ions at different concentrations of CoSO4 reveals that the -value decreases with increasing concentration of the electrolyte. This observation is accounted on the basis of competitive hydration between ions and agar molecules.

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Abstract  

The effect of some alkali metal bromides, iodides and sulphates on the diffusion of bromide, iodide and thallium ions, respectively, is studied at various temperatures. The activation energy required for the process of diffusion of these three ions in different supporting electrolytes have been calculated. It is found that activation energy for a given ion decreases in the reverse order of the charge density of alkali metal ions of the supporting electrolyte. This observed trend in activation energy is explained qualitatively by considering the distortion in the water structure caused by these ions and agar molecules.

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Abstract  

The extent of hydration of agar has been calculated from the self-diffusion studies of Br and I ions in agar gel medium. The measured obstruction effect caused by these macromolecules is related to the extent of hydration by Wang's equation. The value of hydration expressed in terms of grams of bound water per gram of anhydrous agar, in presence of NaI and NH4Br /0.1M/ electrolytes comes out to be about 5.2.

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Abstract  

The non-destructive thermal neutron activation analysis of some commercially available steel samples viz. SS-316, SS-310, SS-304, Tiscral, CA55 and EN 8 is carried out using a252Cf source. The manganese content of these steel samples is estimated by measuring the -activity of56Mn using a single channel analyzer on integration mode and a NaI/Tl/ detector as well as using a high purity germanium detector coupled to a 4K multichannel analyzer. The results obtained by both procedures show reasonable agreement with each other. The nickel content of the various steel samples is also estimated.

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Abstract  

Tracer-diffusion of Zn2+ ions is studied in zinc, manganese and copper sulphates over a concentration range of 10–4 to 0.25M using 1% agar gel medium at 25 °C. A comparison of the experimental and theoretical values of tracer-diffusion coefficients shows a deviation from the theory. This is explained in the light of different types of interactions occurring in the ion-gel-water system. The effect of supporting electrolytes and its concentration on the obstruction effect in the tracer-diffusion of zinc ions is also examined. The obstruction effect decreases with increasing charge density of the cation of the electrolytes at a given concentration and for a particular elecrolyte it decreases with its concentration. These observations are accounted on the basis of competitive hydration between ions and agar macromolecules.

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