Saline water (more commonly known as salt water) is
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
that contains a high concentration of
dissolved salts (mainly
sodium chloride). On the
United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
(USGS)
salinity scale, saline water is saltier than
brackish water
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
, but less salty than
brine. The salt concentration is usually expressed in
parts per thousand (permille, ‰) and
parts per million
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, th ...
(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 one liter of water can dissolve about 357 grams of salt, a concentration of 26.3% w/w. At boiling () the amount that can be dissolved in one liter of water increases to about 391 grams, a concentration of 28.1% w/w.
Properties
At , saturated sodium chloride brine is about 28%
salt by weight. At , brine can only hold about 26% salt. At 20 °C one liter of water can dissolve about 357 grams of salt, a concentration of 26.3%.
The
thermal conductivity of
seawater (3.5% dissolved salt by weight) is 0.6 W/mK at . The thermal conductivity decreases with increasing salinity and increases with increasing temperature.
The salt content can be determined with a
salinometer
A salinometer is a device designed to measure the salinity, or dissolved salt content, of a solution.
Since the salinity affects both the electrical conductivity and the specific gravity of a solution, a salinometer often consist of an ec meter o ...
.
Density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
''ρ'' of brine at various
concentrations and temperatures from can be approximated with a linear equation:
where the values of a
n are:
Electrolysis
About four percent of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
gas produced worldwide is created by
electrolysis. The majority of this hydrogen produced through electrolysis is a side product in the production of
chlorine.
*2 NaCl(aq) + 2 H
2O(l) → 2 NaOH(aq) + H
2(g) + Cl
2(g)
See also
*
Brackish water
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
*
Brine
*
Salinity
*
Seawater
References
External links
{{Authority control
Liquid water
Solutions