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Ionization of Sea-Water

conductivity, temperature and increases


Sea-water is a very complex solution, and it is not possible to calcu late the concentrations of the different ions in it from the older analyses. Since many of these ions affect the P„ and the content, it might be worth while to consider some general facts about the ionization. The simplest method of determining the ionization of a dilute solution of known concentration is by measuring the freezing-point. The accom --A— ..i."me inataj azais VEZIJ1G OW, WIG 1. VICIMAJLI. .11GGLI ing-point lowering (A) to salinity (S) of sea-water from the determinations by H. J. Hansen (Krummel, i, 241). The ratio of A to S is 0.05424 at S =30 and 0.05492 at S = 40, which might be inter preted to indicate that ionization increases the - • 1— 41.- • as 1410 W.111=1141131.1111 inurmasen, WI .1. 4 1,11115 rs only an apparent paradox. In reality, sea-water is a concentrated solution, and it is generally true that the A and osmotic pressure of concentrated solutions increase more rapidly than the concentration.

Electric conductivity experiments show exactly the opposite relation. Figure 23, plotted from the data of Ruppin (Krummel, 291), shows that the conductivity increases less rapidly than the concentration, and that this is almost equally true at various temperatures. Con ductivity data must be considered with some caution, however, since viscosity influences conductivity. This is apparent in the change of conductivity with temperature shown in figure 24. It will be noticed that conductivity of sea-water increases very rapidly with temperature, and almost in direct proportion to it. The conductivity is doubled by a rise in temperature of 30°, and it is very improbable that ionization increases so rapidly. Rise in temperature decreases the viscosity of water and in this way increases the conductivity. It is probable that ionization is increased slowly by dilution and also by rise in temperature of sea-water.