Salt water
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Salt water or saline water is water that contains a high concentration of dissolved salts (mainly sodium chloride), a saline solution. Although term "salt water" is mostly used for sea and oceanic water, while the term "saline water" refers to any water containing an amount of salt, the use of both terms can vary, depending on the language or context.
The amount of salt dissolved in a body of water is called salinity.
Definition
On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, but less salty than brine. The salt concentration is usually expressed in parts per thousand (permille, ‰) and parts per million (ppm). The USGS salinity scale defines three levels of saline water. The salt concentration in slightly saline water is 1,000 to 3,000 ppm (0.1–0.3%); in moderately saline water is 3,000 to 10,000 ppm (0.3–1%); and in highly saline water is 10,000 to 35,000 ppm (1–3.5%). Seawater has a salinity of roughly 35,000 ppm, equivalent to 35 grams of salt per one liter (or kilogram) of water. The saturation level is only nominally dependent on the temperature of the water. At 20 °C (68 °F) one liter of water can dissolve about 357 grams of salt, a concentration of 26.3% w/w. At boiling (100 °C (212 °F)) the amount that can be dissolved in one liter of water increases to about 391 grams, a concentration of 28.1% w/w.[1]
Uses
Unlike pure water, salt water is electrically conductive, and thus can be used to conduct electrical current or to perform electrolysis. Sea water however, is too diluted to prepare significant amounts of chlorate, and brine is the better choice.
Saline water is not miscible with many alcohols or other water miscible solvents, property which can be used to separate the solvent from the water.
Medical grade saline solutions are used in transfusions, eyedrops or in eyewash stations.
