Editing Ammonia (section)

=== Solvent properties ===
Ammonia readily [[solubility|dissolves]] in water. In an aqueous solution, it can be expelled by boiling. The [[water|aqueous]] solution of ammonia is [[Base (chemistry)|basic]], and may be described as aqueous ammonia or [[ammonium hydroxide]].<ref>{{Cite web |date=January 12, 2017 |title=Medical Management Guidelines for Ammonia |url=https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=7&toxid=2 |website=Agency for Toxic Substances and Disease Registry}}</ref> The maximum concentration of ammonia in water (a [[saturated solution]]) has a [[specific gravity]] of 0.880 and is often known as '.880 ammonia'.<ref>{{Cite book |last=Hawkins |first=Nehemiah |url=https://books.google.com/books?id=Z14wAAAAMAAJ |title=Hawkins' Mechanical Dictionary: A Cyclopedia of Words, Terms, Phrases and Data Used in the Mechanic Arts, Trades and Sciences |date=1909 |publisher=T. Audel |pages=15 |language=en}}</ref>

{|class="wikitable mw-collapsible"
|+Thermal and physical properties of saturated liquid ammonia<ref name="Stalke, D.-2016" /><ref name="Combellas-2001" />
!Temperature<br>(°C)
!Density<br>(kg/m<sup>3</sup>)
!Specific heat<br>(kJ/(kg·K))
!Kinematic<br>viscosity<br>(m<sup>2</sup>/s)
!Thermal<br>conductivity<br>(W/(m·K))
!Thermal<br>diffusivity<br>(m<sup>2</sup>/s)
!Prandtl<br>Number
!Bulk modulus<br>(K<sup>−1</sup>)
|-
| −50
|703.69
|4.463
|4.35×10<sup>−7</sup>
|0.547
|1.74×10<sup>−7</sup>
|2.6
|
|-
| −40
|691.68
|4.467
|4.06×10<sup>−7</sup>
|0.547
|1.78×10<sup>−7</sup>
|2.28
|
|-
| −30
|679.34
|4.476
|3.87×10<sup>−7</sup>
|0.549
|1.80×10<sup>−7</sup>
|2.15
|
|-
| −20
|666.69
|4.509
|3.81×10<sup>−7</sup>
|0.547
|1.82×10<sup>−7</sup>
|2.09
|
|-
| −10
|653.55
|4.564
|3.78×10<sup>−7</sup>
|0.543
|1.83×10<sup>−7</sup>
|2.07
|
|-
|0
|640.1
|4.635
|3.73×10<sup>−7</sup>
|0.540
|1.82×10<sup>−7</sup>
|2.05
|
|-
|10
|626.16
|4.714
|3.68×10<sup>−7</sup>
|0.531
|1.80×10<sup>−7</sup>
|2.04
|
|-
|20
|611.75
|4.798
|3.59×10<sup>−7</sup>
|0.521
|1.78×10<sup>−7</sup>
|2.02
|2.45×10<sup>−3</sup>
|-
|30
|596.37
|4.89
|3.49×10<sup>−7</sup>
|0.507
|1.74×10<sup>−7</sup>
|2.01
|
|-
|40
|580.99
|4.999
|3.40×10<sup>−7</sup>
|0.493
|1.70×10<sup>−7</sup>
|2
|
|-
|50
|564.33
|5.116
|3.30×10<sup>−7</sup>
|0.476
|1.65×10<sup>−7</sup>
|1.99
|
|}

{|class="wikitable mw-collapsible"
|+Thermal and physical properties of ammonia ({{chem2|NH3}}) at atmospheric pressure<ref name="Stalke, D.-2016" /><ref name="Combellas-2001" />
!Temperature<br>(K)
!Temperature (°C)
!Density<br>(kg/m<sup>3</sup>)
!Specific heat<br>(kJ/(kg·K))
!Dynamic<br>viscosity<br>(kg/(m·s))
!Kinematic<br>viscosity<br>(m<sup>2</sup>/s)
!Thermal<br>conductivity<br>(W/(m·K))
!Thermal<br>diffusivity<br>(m<sup>2</sup>/s)
!Prandtl<br>Number
|-
|273
| −0.15
|0.7929
|2.177
|9.35×10<sup>−6</sup>
|1.18×10<sup>−5</sup>
|0.0220
|1.31×10<sup>−5</sup>
|0.90
|-
|323
|49.85
|0.6487
|2.177
|1.10×10<sup>−5</sup>
|1.70×10<sup>−5</sup>
|0.0270
|1.92×10<sup>−5</sup>
|0.88
|-
|373
|99.85
|0.559
|2.236
|1.29×10<sup>−5</sup>
|1.30×10<sup>−5</sup>
|0.0327
|2.62×10<sup>−5</sup>
|0.87
|-
|423
|149.85
|0.4934
|2.315
|1.47×10<sup>−5</sup>
|2.97×10<sup>−5</sup>
|0.0391
|3.43×10<sup>−5</sup>
|0.87
|-
|473
|199.85
|0.4405
|2.395
|1.65×10<sup>−5</sup>
|3.74×10<sup>−5</sup>
|0.0467
|4.42×10<sup>−5</sup>
|0.84
|-
|480
|206.85
|0.4273
|2.43
|1.67×10<sup>−5</sup>
|3.90×10<sup>−5</sup>
|0.0492
|4.74×10<sup>−5</sup>
|0.822
|-
|500
|226.85
|0.4101
|2.467
|1.73×10<sup>−5</sup>
|4.22×10<sup>−5</sup>
|0.0525
|5.19×10<sup>−5</sup>
|0.813
|-
|520
|246.85
|0.3942
|2.504
|1.80×10<sup>−5</sup>
|4.57×10<sup>−5</sup>
|0.0545
|5.52×10<sup>−5</sup>
|0.827
|-
|540
|266.85
|0.3795
|2.54
|1.87×10<sup>−5</sup>
|4.91×10<sup>−5</sup>
|0.0575
|5.97×10<sup>−5</sup>
|0.824
|-
|560
|286.85
|0.3708
|2.577
|1.93×10<sup>−5</sup>
|5.20×10<sup>−5</sup>
|0.0606
|6.34×10<sup>−5</sup>
|0.827
|-
|580
|306.85
|0.3533
|2.613
|2.00×10<sup>−5</sup>
|5.65×10<sup>−5</sup>
|0.0638
|6.91×10<sup>−5</sup>
|0.817
|}

Liquid ammonia is a widely studied nonaqueous ionising solvent. Its most conspicuous property is its ability to dissolve alkali metals to form highly coloured, electrically conductive solutions containing [[solvated electron]]s. Apart from these remarkable solutions, much of the chemistry in liquid ammonia can be classified by analogy with related reactions in [[aqueous solution]]s. Comparison of the physical properties of {{chem2|NH3}} with those of water shows {{chem2|NH3}} has the lower melting point, boiling point, density, [[viscosity]], [[dielectric constant]] and [[electrical conductivity]]. These differences are attributed at least in part to the weaker hydrogen bonding in {{chem2|NH3}}. The ionic self-[[dissociation constant]] of liquid {{chem2|NH3}} at −50&nbsp;°C is about 10<sup>−33</sup>.
[[File:Ammonia Train.jpg|thumb|A train carrying anhydrous ammonia]]

{| class="wikitable"
|-
!
! Solubility (g of salt per 100&nbsp;g liquid {{chem2|NH3}})
|-
| [[Ammonium acetate]]
| 253.2
|-
| [[Ammonium nitrate]]
| 389.6
|-
| [[Lithium nitrate]]
| 243.7
|-
| [[Sodium nitrate]]
| 97.6
|-
| [[Potassium nitrate]]
| 10.4
|-
| [[Sodium fluoride]]
| 0.35
|-
| [[Sodium chloride]]
| 157.0
|-
| [[Sodium bromide]]
| 138.0
|-
| [[Sodium iodide]]
| 161.9
|-
| [[Sodium thiocyanate]]
| 205.5
|}

Liquid ammonia is an ionising solvent, although less so than water, and dissolves a range of ionic compounds, including many [[nitrate]]s, [[nitrite]]s, [[cyanide]]s, [[thiocyanate]]s, [[Cyclopentadienyl complex|metal cyclopentadienyl complexes]] and [[metal bis(trimethylsilyl)amides]].<ref name="Stalke, D.-2016">{{cite journal|author1=Neufeld, R.|author2=Michel, R.|author3=Herbst-Irmer, R.|author4=Schöne, R.|author5=Stalke, D.|year=2016|title=Introducing a Hydrogen-Bond Donor into a Weakly Nucleophilic Brønsted Base: Alkali Metal Hexamethyldisilazides (MHMDS, M = Li, Na, K, Rb and Cs) with Ammonia|journal=[[Chem. Eur. J.]]|volume=22|issue=35|pages=12340–12346|doi=10.1002/chem.201600833|pmid=27457218}}</ref> Most ammonium salts are soluble and act as acids in liquid ammonia solutions. The solubility of [[halide]] salts increases from [[fluoride]] to [[iodide]]. A saturated solution of [[ammonium nitrate]] ('''Divers' solution''', named after [[Edward Divers]]) contains 0.83&nbsp;mol solute per mole of ammonia and has a [[vapour pressure]] of less than 1&nbsp;bar even at {{convert|25|C|0|abbr=on}}.  However, few [[oxyanion]] salts with other cations dissolve.<ref>{{cite book|url=https://archive.org/details/cftri.2662nonaqueoussolven0000ludw/page/45/|page=45|title=Non-aqueous solvents|first1=Ludwig&nbsp;F.|last1=Audrieth|first2=Jacob|last2=Kleinberg|publisher=John Wiley & Sons|location=New York|year=1953|lccn=52-12057}}</ref>

Liquid ammonia will dissolve all of the [[alkali metal]]s and other [[electronegativity|electropositive]] metals such as [[calcium|Ca]],<ref>{{cite encyclopedia|year=2001|title=Calcium–Ammonia|encyclopedia=Encyclopedia of Reagents for Organic Synthesis|doi=10.1002/047084289X.rc003|isbn=978-0471936237|author=Edwin M. Kaiser}}</ref> [[strontium|Sr]], [[barium|Ba]], [[europium|Eu]] and [[ytterbium|Yb]] (also [[magnesium|Mg]] using an electrolytic process<ref name="Combellas-2001">{{cite journal|last1=Combellas|first1=C|last2=Kanoufi|first2=F|last3=Thiébault|first3=A|year=2001|title=Solutions of solvated electrons in liquid ammonia|journal=Journal of Electroanalytical Chemistry|volume=499|pages=144–151|doi=10.1016/S0022-0728(00)00504-0}}</ref>). At low concentrations (<0.06&nbsp;mol/L), deep blue solutions are formed: these contain metal cations and [[solvated electron]]s, free electrons that are surrounded by a cage of ammonia molecules.

These solutions are strong reducing agents. At higher concentrations, the solutions are metallic in appearance and in electrical conductivity. At low temperatures, the two types of solution can coexist as [[Wiktionary:immiscible|immiscible]] phases.

==== Redox properties of liquid ammonia ====
{{See also|Redox}}
[[File:Liquid ammonia bottle.jpg|thumb|upright|Liquid ammonia bottle]]

{| class="wikitable" style="text-align:center"
!
! [[Standard electrode potential|''E''°]] (V, ammonia)
! [[Standard electrode potential|''E''°]] (V, water)
|-
| {{chem2|Li+ + e− ⇌ Li}}
| −2.24
| −3.04
|-
| {{chem2|K+ + e− ⇌ K}}
| −1.98
| −2.93
|-
| {{chem2|Na+ + e− ⇌ Na}}
| −1.85
| −2.71
|-
| {{chem2|Zn(2+) + 2 e− ⇌ Zn}}
| −0.53
| −0.76
|-
| {{chem2|2 [NH4]+ + 2 e− ⇌ H2 + 2 NH3}}
| 0.00
| —
|-
| {{chem2|Cu(2+) + 2 e− ⇌ Cu}}
| +0.43
| +0.34
|-
| {{chem2|Ag+ + e− ⇌ Ag}}
| +0.83
| +0.80
|}

The range of thermodynamic stability of liquid ammonia solutions is very narrow, as the potential for oxidation to dinitrogen, [[Standard electrode potential|''E''°]] ({{chem2|N2 + 6 [NH4]+ + 6 e− ⇌ 8 NH3}}), is only +0.04&nbsp;V. In practice, both oxidation to dinitrogen and reduction to dihydrogen are slow. This is particularly true of reducing solutions: the solutions of the alkali metals mentioned above are stable for several days, slowly decomposing to the [[Amide|metal amide]] and dihydrogen. Most studies involving liquid ammonia solutions are done in reducing conditions; although oxidation of liquid ammonia is usually slow, there is still a risk of explosion, particularly if [[transition metal]] ions are present as possible catalysts.