電解質 溶液의 濃度에 따른 粘度係數와 表面張力에 關한 硏究 = Studies on the Viscosity Coefficient and Surface Tension of Electrolytic Solutions as a Function of the Concentration

다국어 초록 (Multilingual Abstract)

The viscosity and surface tension of aqueous solutions of electolytes such as KCI, NaI, KI, NaBr, CaBr_2, and LiCl have been measured over a fairly wide range of concentraion variation.
To secure more accurate measurement, Ostwald viscometer and differential capillarimeter were made with pyrex glass both of which were utillized by Grinnell Jones and his co-worker.
Timing system in our viscometer, unlike ordinary ones currently used, was entirely functioned by electronics system and pulse counter of 510 cycles/sec, thus enabling us to make more accurate time measurement.
The results obtained were in good agreement with the Jone's value except extremely dilute range of which were not measured so far.
As the experimental data obtained were in good agreement with the Jones' values, Jones-Dole equation for the viscosity of electolytic solutions were deduced.
η_r=1+0.0052√c-0.016c+0.008c^2 (KCl at 30℃)
η_r=1+0.0220√c-0.129c+0.030c^2 (Kl at 25℃)
η_r=1+0.0240√c-0.064c+0.033c^2 (NaI at 25℃)
η_r=1-0.054√c+1.23c-2.07c^2 (NaBr at 25℃)
η_r=1+0.070√c-0.177c+0.565c^2 (CaBr_2 at 25℃)
η_r=1-0.037√c+0.881c-0.610c^2 (LiCl at 25℃)
For surface tension the data were in good agreement with Jones' value and M. Dole's equation were in good agreement. But we have made some virial equation like that of viscosity as follows;
σ_r=1-0.0048√c+0.0799c-0.063c^2 (KCl at 30℃)
σ_r=1-0.0058√c+0.0983c-0.069c^2 (Kl at 25℃)
σ_r=1-0.0052√c+0.0703c-0.409c^2 (NaI at 25℃)
σ_r=1+0.204√c-0.638c+0.953c^2 (NaBr at 25℃)
σ_r=1+2.98√c-8.21c+3.98c^2 (CaBr_2 at 25℃)
σ_r=1-0.560√c+4.00c+0.09c^2 (LiCl at 25℃)
G. Jones et al have investigated the relation between viscosity and concentration of various electolytic solutions, and passed upon qualitative tendencies, they classified electolytic solutions into two categories. For solutions which belong to the first type, the viscosity at first increase in proportion to concentration until it reaches maximum value, to be followed hereafter the decrease of viscosity.
Other solution that may be grouped in latter category show quite different viscosity-concentration relation, the viscosity decreases at first with the increase of concentration and passing the minimum, the viscosity starts to increase.
According to our result viscosity and concentration curve prolonged in extremely dilute range of concentraion, most of electrolytic aqueous solution increase the viscosity as concentration increase, but pass the maximum and decrease the viscosity as concentration increase but the concentraion which shows the viscosity manimum is different according to the kind of salts. In concentraion range viscosity of solution increase again and made a oscillation of sin curve.
The reason why the effect of viscosity varies with concentraion we have conclude that there are three factors.
The presence of a few ions assists the formation of water arrangement around ions, and increase the viscosity.
In dilute range, the hydrated ion cut hydrogen bond locally, to attract loose tetrahedral structure closer, thereby resulting the increase of fluidity and have decrease of viscosity.
In concentration range, the number of hydrated ions increase (most free water is exhausted), and the formation of large particles cause again the increase of viscosity.
Therefore the viscosity and concentration curves of the most electolytic solutions follow oscillation of rough sinusoidal pattern.