View source for Saline water

{{Short description|Water that contains a high concentration of dissolved salts}}
{{redirect|Salt water|water in the oceans|Seawater|other uses}}
{{for multi|saline solution in medicine and life science|Saline (medicine)||Saline (disambiguation)}}
{{Water salinity}}

'''Saline water''' (more commonly known as '''salt water''') is [[water]] that contains a high concentration of [[solvation|dissolved]] [[salt (chemistry)|salts]] (mainly [[sodium chloride]]). 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.<ref>{{Cite web|date=c. 2004|title=Sodium Chloride MSDS|url=https://www.sigmaaldrich.com/catalog/product/sial/s7653?lang=en&region=CA&cm_sp=Insite-_-caSrpResults_srpRecs_srpModel_sodium%20chloride-_-srpRecs3-1|website=Sigma Aldrich |url-status=dead |archive-url=https://web.archive.org/web/20210209190004/https://www.sigmaaldrich.com/catalog/product/sial/s7653?lang=en&region=US&cm_sp=Insite-_-caSrpResults_srpRecs_srpModel_sodium%20chloride-_-srpRecs3-1 |archive-date=2021-02-09}}</ref> At {{Convert|20|C|F|abbr=|sp=us}} one liter of water can dissolve about 357 grams of salt, a concentration of 26.3 [[Mass fraction (chemistry)|percent by weight]] (% w/w). At {{Convert|100|C|F|abbr=|sp=us}} (the boiling temperature of pure water), the amount of salt that can be dissolved in one liter of water increases to about 391 grams, a concentration of 28.1% w/w.

== Properties ==
[[File:WatNaCl.png|thumb|upright=1.25|Water-NaCl [[phase diagram]]]]

{|class="wikitable" style="text-align:right"
|+ Properties of water-NaCl mixtures<ref>{{RubberBible86th|pages=8–71, 8–116}}</ref>
|-
!NaCl, [[wt%]]!!Freezing point (°C)!! Freezing point (°F)!! [[Density]]<!--<ref group=note name=Temperature>At some ambient temperature (0°C).</ref>-->{{efn|At some ambient temperature}} (g/cm<sup>3</sup>)!! [[Refractive index]]{{efn|At some ambient temperature}} at 589&nbsp;nm!![[Viscosity]]{{efn|At some ambient temperature (20°C)}} (cP )
|-
|0|| 0|| 32|| 0.99984|| 1.3330|| 1.002
|-
|0.5|| −0.3|| 31.46|| 1.0018|| 1.3339|| 1.011
|-
|1|| −0.59|| 30.94|| 1.0053|| 1.3347|| 1.02
|-
|2|| −1.19|| 29.86|| 1.0125|| 1.3365|| 1.036
|-
|3|| −1.79|| 28.78|| 1.0196|| 1.3383|| 1.052
|-
|4|| −2.41|| 27.66|| 1.0268|| 1.3400|| 1.068
|-
|5|| −3.05|| 26.51|| 1.0340|| 1.3418|| 1.085
|-
|6|| −3.7|| 25.34|| 1.0413|| 1.3435|| 1.104
|-
|7|| −4.38|| 24.12|| 1.0486|| 1.3453|| 1.124
|-
|8|| −5.08|| 22.86|| 1.0559|| 1.3470|| 1.145
|-
|9|| −5.81|| 21.54|| 1.0633|| 1.3488|| 1.168
|-
|10|| −6.56|| 20.19|| 1.0707|| 1.3505|| 1.193
|-
|12|| −8.18|| 17.28|| 1.0857|| 1.3541|| 1.25
|-
|14|| −9.94|| 14.11|| 1.1008|| 1.3576|| 1.317
|-
|16|| −11.89|| 10.60|| 1.1162|| 1.3612|| 1.388
|-
|18|| −14.04|| 6.73|| 1.1319|| 1.3648|| 1.463
|-
|20|| −16.46|| 2.37|| 1.1478|| 1.3684|| 1.557
|-
|{{efn|[[Eutectic mixture]]}}23.3|| −21.1|| −5.98|| 1.179|| || 
|-
|26|| −19.18|| −2.52|| 1.193|| 1.3795|| 1.676
|}
{{notelist}}
<!--{{Reflist|group=note}}-->

At {{Convert|100|C|F K|abbr=|sp=us}}, saturated sodium chloride brine is about 28% [[salt]] by weight. At {{Convert|0|C|F K|abbr=|sp=us}}, brine can only hold about 26% salt.<ref>CRC Handbook of Chemistry and Physics, 63rd Edition 1982-1983.</ref> At 20&nbsp;°C one liter of water can dissolve about 357 grams of salt, a concentration of 26.3%.<ref>{{Cite web|url=https://www.chem.wisc.edu/deptfiles/genchem/sstutorial/Text11/Tx112/tx112.html|title=Solubility|website=University of Wisconsin Fundamentals of Chemistry|url-status=live|archive-url=https://web.archive.org/web/20160331150210/https://www.chem.wisc.edu/deptfiles/genchem/sstutorial/Text11/Tx112/tx112.html|archive-date=31 March 2016|access-date=6 November 2014}}</ref>

The [[thermal conductivity]] of [[seawater]] (3.5% dissolved salt by weight) is 0.6 W/mK at {{Convert|25|C|F|abbr=|sp=us}}.<ref>[http://web.mit.edu/lienhard/www/Thermophysical_properties_of_seawater-DWT-16-354-2010.pdf Thermophysical properties of seawater: a review of existing correlations and data] Paper published in April 2010 on ''web.mit.edu''. Retrieved 2021-03-11.</ref> The thermal conductivity decreases with increasing salinity and increases with increasing temperature.
<ref>https://handbook.ashrae.org/Handbooks/F17/SI/F17_Ch31/figures/F31sf08.jpg Plots of thermal conductivity vs. temperature for 0, 5, ... 25 w/w NaCl/water solutions. Retrieved 2020-11-27.</ref>
<ref>{{Cite web|url=http://twt.mpei.ac.ru/tthb/2/Tab-5-5-13-2-Ther-Cond-Seawater.html|title=Thermal conductivity of seawater and its concentrates|website=twt.mpei.ac.ru|access-date=2018-02-16}}</ref>
The salt content can be determined with a [[salinometer]].

[[Density]] ''ρ'' of brine at various [[concentration]]s and temperatures from {{Convert|200 to 575|C|F|abbr=|sp=us}} can be approximated with a linear equation:<ref>{{cite journal |last=Dittman |first=Gerald L. |date=February 16, 1977 |title=Calculation of Brine Properties. |location=Livermore CA |journal= Lawrence Livermore Laboratories |doi=10.2172/7111583 |url=http://www.osti.gov/bridge/servlets/purl/7111583-l9lvkU/native/7111583.pd }}</ref>

<math>\rho [lb/ft^3]= a_3 - (a_2 \cdot T[F])</math>

where the values of a<sub>n</sub> are:

{| class="wikitable" style="text-align:right"
|-
! Weight % !! a<sub>2</sub> !! a<sub>3</sub>
|-
| 5 || 0.043 || 72.60
|-
| 10 || 0.039 || 73.72
|-

| 15 || 0.035 || 74.86
|-
| 20 || 0.032 || 76.21
|-
| 25 || 0.030 || 77.85
|}

===Electrolysis===
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 H<sub>2</sub>O(l) → 2 NaOH(aq) + H<sub>2</sub>(g) + Cl<sub>2</sub>(g)

== See also ==
* [[Brackish water]]
* [[Brine]]
* [[Salinity]]
* [[Seawater]]

== References ==
{{Reflist}}

==External links==
{{Commons category-inline|Saline water}}

{{Authority control}}

[[Category:Liquid water]]
[[Category:Solutions]]