Solubility of Salts in Sea Water
The solubility of calcium carbonate in sea water has been examined in some detail, but relatively little is known about the other constituents. Because of the complex nature of sea water and the effect of other ions upon the activity of any one, the solubility product of a single salt in distilled water cannot be applied to sea water. Cooper (1937b) considers that most of the iron in sea water is not in true solution, but is present in some colloidal form, as the solubility product for the hydroxide is
Thompson and his co-workers (for example, Igelsrud and Thompson, 1936) have carried out extensive phase-rule studies of solutions containing some of the salts in sea water, but so far they have not extended their investigations to natural water.
Some indication of the great solubility of the major constituents is afforded by data on the separation of salts when sea water is frozen (p. 217). Somewhat similar data may be obtained from the evaporation studies by Usiglio (Thompson and Robinson, 1932), which again bring out the fact that sea water is far from saturated with most of the constituents.
|Salt||K Distilled water||K' Sea water S = 35 ‰, ϑ = 20°||Ionic product Cl = 19.0 ‰, ϑ = 20° pH = 8.2|
|CaCO3||0.5 × 10− 3||50 × 10− 3||270 × 10− 3|
|MgCO33H2O||0.1 × 10− 4||3.1 × 10− 4||0.14 × 10− 4|
|SrCO3||0.3 × 10− 9||500 × 10− 9||39 × 10− 9|
|Mg(OH)2||1 × 10− 11||5 × 10− 11||0.02 × 10− 11|