Effects of different sized concentration differences across free diffusion boundaries and comparison of Gouy and Rayleigh diffusion measurements using Nacl-KCl-H{sub 2}O
- Lawrence Livermore National Lab., IL (United States); and others
Diffusion was systematically studied in the ternary system NaCl (0.5M)-KCl (0.5M)-H{sub 2}O at 25{degrees}C. There were four purposes. First, current methods to extract D{sub ij} from Gouy and Rayleigh interferometry data depend on treating the D{sub ij} as effectively constant. If concentration differences {Delta}C{sub i} across the boundary are large, this may not be true. To explore this issue, for sets of experiments were performed. EAch set had four experiments with approximately the same total number of fringes J. Each set also had the same corresponding {Delta}C{sub 1}/{Delta}C{sub 2} ratios as the other three, but the {Delta}C{sub i} were adjusted such that the four sets had J {approx} 30, 60, 90, and 120, respectively. No clear dependence of the D{sub ij} on {Delta}C{sub i} was found within their realistic errors. Second, the Gosting diffusiometer can yield both Rayleigh and Gouy fringe patterns during the same experiment. Therefore, a new method for analyzing Gouy fringe positions (Miller; program TNY) can be compared to the classical one (Fujita-Gosting; program RFG). The D{sub ij} from both analyses agree well. Fourth, we compared results from the Gosting diffusiometer with those at the same composition from other diffusiometers; one data set by O`Donnell and Gosting from an older Gouy apparatus, and three Rayleigh sets at different J values from other older Model H diffusiometer. Results from older diffusiometers were more scattered, but corresponding D{sub ij} agree within realistic errors. As reported previously, realistic errors are approximately four times the statistical errors obtained by least squares. Recommended Rayleigh and Gouy D{sub ij} are presented for this composition.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 625689
- Journal Information:
- Journal of Solution Chemistry, Vol. 25, Issue 12; Other Information: PBD: 1996
- Country of Publication:
- United States
- Language:
- English
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