Brine

Brine is a solution of salt (usually sodium chloride) in water. In different contexts, brine may refer to salt solutions ranging from about 3.5% (a typical concentration of seawater, or the lower end of solutions used for brining foods) up to about 26% (a typical saturated solution, depending on temperature). Other levels of concentration are called in different names:

It is held that 0 °F (−17.78 °C) was initially set as the zero point in the Fahrenheit temperature scale, as it was the coldest temperature that Daniel G. Fahrenheit could reliably reproduce by freezing brine.

Properties


At 100 °C (373.15 K, 212 °F), saturated sodium chloride brine is about 28% salt by weight i.e. 39.12 g salt dissolves in 100 mL of water at 100 °C. At 0 °C (273.15 K, 32 °F), brine can only hold about 26% salt.

The thermal conductivity of seawater (3.5% dissolved salt by weight) is 0.6 W/mK at 25 °C. The thermal conductivity decreases with increasing salinity and increases with increasing temperature; these graphs and online calculations plot thermal conductivity for varying salinity and temperature:

Density of brine at various concentrations and temperatures can be approximated with a linear equation: Density (lb/ft3)= a3 - (a2*Temperature (F)) where the values of an are:

Electrolysis of brine
About four percent of hydrogen 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 H2O(l) → 2 Na(aq) + H2(g) + Cl2(g)

Refrigerating fluid
Brine is a common fluid used in large refrigeration installations for the transport of thermal energy from place to place. It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine is &minus;21.1 °C (&minus;6.0 °F) at 23.3wt% NaCl. This is called the eutectic point.

De-icing
In colder temperatures, brine can be used to de-ice or reduce freezing temperatures on roads. Certain forms of road salt, such as magnesium chloride, have been banned in some jurisdictions because of their increased impact to road infrastructure such as concrete bridges, as well as roadside vegetation.

Culinary
In cooking, brine is used for food brining and salting.

Hydrology
In hydrology, brine is a form of salt water, namely, water with relatively high concentration of salt (usually sodium chloride).