Chemical properties of seawater?

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Seawater is mostly water but contains 3.5% dissolved salts, including sodium chloride. It is a different environment from freshwater, and many animals cannot adapt to living in both. Seawater contains various salts, including calcium chloride, sulfates, magnesium, calcium, potassium, and minor constituents. Extracting uranium or gold from seawater has not been economically viable. The salts in seawater come from land and volcanic outgassing. Seawater is unsafe for human consumption, and drinking it increases the probability of death. Scientists recommend mixing it with fresh water in a 1:2 ratio to increase the likelihood of survival.

Seawater is mostly (~96.5%) water, but contains significant amounts of dissolved salts (~3.5%), which are mostly, but not all, sodium chloride, which is identical to table salt. The unique chemical properties of seawater mean that it is a drastically different living environment from fresh water and many animals that live in it have never adapted to living in fresh water. Species adapted to fresh water, such as fish in landlocked lakes in Africa, cannot survive in salt water. Seawater is about 2.5% denser than fresh water.

In addition to calcium chloride salts, seawater also contains sulfates (7.7% dissolved salts), magnesium (3.7%), calcium (1.2%), potassium (1.1%) and minor constituents (0.7%), including traces of inorganic carbon (0.2%), bromide (0.08%), uranium (0.00000001%) and gold (similar amount). Various schemes have been proposed to extract uranium or gold from this water, but neither has proven economically viable. Fritz Haber, the German scientist best known for his invention of the Haber process and Zyklon poison gas, spent the last years of his life trying to find an efficient way to extract large quantities of gold from seawater so that Germany could pay his war debts. Naturally, this effort failed.

The origin of the salts in seawater are both land and salts that were present on the surface of the Earth when the oceans first formed, which may have been 100 million years after the formation of the Earth. The theory that salts are derived from rainwater runoff originated with Sir Edmund Halley in 1715. Specifically, the sodium in ocean sodium chloride comes mainly from when the oceans formed, and the chloride comes from volcanic outgassing on ocean floors.

Seawater is known to be unsafe for human consumption. Since it contains 3.5% salt and the human body strictly maintains sodium chloride at 0.9% blood by weight, the kidneys have to consume extra water to dissolve the excess salts. According to historical data of life raft trips, the probability of death for those who drink sea water is about 39%, while the probability of death for those who do not drink it is only 3%. When lost at sea, scientists recommend instead drinking it mixed with fresh water, in a 1:2 ratio, slowly increasing as the fresh water runs out. This is milder than the metabolic impact of switching from fresh to pure salt water and increases the likelihood of survival.




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