A New Interferometric Method for the Determination of Diffusion Coefficients of Very Dilute Solutions.

Bryngdahl, Olof; Lagerström, Gösta; Frydman, Mina; Sillén, Lars Gunnar

doi:10.3891/acta.chem.scand.11-1017

Cited by 29 publications

(4 citation statements)

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“…The filled circles in Figure 1 are the diffusion coefficients of Bu4NBr obtained by Pepela, Steel, and Dunlop15 using shearing interference optics. 16 It can be seen that results from the shearing diffusiometer and the Gouy method agree within the precision of the former.…”

Section: Resultsmentioning

confidence: 61%

Diffusion coefficients of tetrabutylammonium halides in water at 25.deg.

Kim¹,

Revzin²,

Gosting³

1973

J. Phys. Chem.

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Publication costs assisted by the National Institute of Arthritis and Metabolic Diseases Diffusion coefficients measured with a new optical diffusiometer are reported for tetrabutylammonium halides (Bu-iNX) in water at 25°. The concentration range studied extended up to 0.6 M for Bu-tNCl, 0.8 M for BuéNBr, and 0.06 M for the less soluble Bu-iNI. The diffusion coefficients for a given concentration decreased with increasing anion size while the mobility terms, which were obtained by dividing the diffusion coefficients by a thermodynamic term, showed the reverse order. Refractive index derivatives were also determined as well as density data from which partial molal volumes were computed.

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Section: Resultsmentioning

confidence: 61%

Diffusion coefficients of tetrabutylammonium halides in water at 25.deg.

Kim¹,

Revzin²,

Gosting³

1973

J. Phys. Chem.

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“…They yield the curves in Figure 5. The comparison with literature data in the CSN0 3 rich limiting region shows a good agreement for the (Cs,Ag)N0 3 system, regardless the far-way extrapolation from the measured region (meltingpoint of pure CSN0 3 : 417 °C). For the (Li, Ag)N0 3 system a statement is difficult: On the one hand it is not unusual that lithium shows a deviating behaviour from the other alkali metals.…”

Section: Resultsmentioning

confidence: 55%

“…The wave-front-shearing interferometer used was described by Bryngdahl [3] and first applied to molten salts by Gustafsson and coworkers [4]. The only principal difference between our and Gustafssons method was the way in which the initial "plane source" was formed.…”

Section: Methodmentioning

confidence: 99%

Concentration Dependence of the Interdiffusion Coefficients in Molten Alkali Nitrate — Silver Nitrate Mixtures

Hahne

Richter

1983

Zeitschrift Für Naturforschung A

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To measure the composition dependence of the interdiffusion coefficients in molten mixtures of alkali nitrates and silver nitrate, a wave-front-shearing interferometer, together with an initial "plane source" was used.With this technique, the diffusion coefficients were measured in nearly differential steps in the three mixtures (Na,Ag)N0 3 , (K,Ag)N0 3 , and (Rb,Ag)N0 3 at 300°C. The composition dependence of the diffusion coefficients D of all three systems could be described by parabolas of the formwhere x 2 denotes the mole fraction of the silver nitrate. The three coefficients a, b, and c all show a clear proportionality to the radii of the alkali ions. Thus an extrapolation to the not measured systems (Li,Ag)N0 3 and (Cs,Ag)N0 3 was possible.From the theoretical point of view, it is advantageous to measure interdiffusion coefficients in simple binary melts as a function of composition in nearly differential steps. There are two reasons for this:1. The reference velocity o in the equation of the diffusion current density 7, of the component i(c, = concentration, i\ = mean velocity of component /') is usually the "mean volume velocity" This reference velocity is equal to zero, if the partial molar volumes are independent of composition. This is also a good approach for the case that the applied concentration difference is small enough. In Ficks second lawthe diffusion coefficient is generally not composition independent. The error in assuming a concentration independent diffusion coefficient is the Reprint requests to Prof. Dr. J. Richter, Institut für Physik. Chemie, Technische Hochschule Aachen, D-5100 Aachen.smaller, the closer the two concentrations are together at the start of the measurement [2], There is a variety of methods described in literature to measure interdiffusion coefficients in molten salts, but most of them have certain disadvantages. Some of them, e.g. the polarographic and the chronopotentiometric method, work satisfactory only in the region of "dilute solutions". The others, e.g. the "fritted disc" and the diaphragm cell, need relatively high concentration differences to achieve a sufficient precision.By modifying an approved interferometric method. we succeeded in measuring interdiffusion coefficients with an applied initial composition difference of 2 mole percent. ExperimentalMethod: The wave-front-shearing interferometer used was described by Bryngdahl [3] and first applied to molten salts by Gustafsson and coworkers [4]. The only principal difference between our and Gustafssons method was the way in which the initial "plane source" was formed. While Gustafsson threw a solid crystal of silver nitrate to the bottom of a cell filled with molten alkali nitrate, this procedure could not be used in our case.We filled our cell with a nitrate mixture, the mole fraction of silver nitrate being .v 2 , and brought a

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“…The basic design of the interferometer used was that of Inglestam (13,14) and Bryngdahl (2), and consisted of an optical bench, lens system, and polarized laser light source.…”

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confidence: 99%