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{{Short description|Chemical compound}}
{{Redirect|Hot ice}}
{{chembox {{chembox
| Verifiedfields = changed
| verifiedrevid = 464392486
| Watchedfields = changed
| Name = Sodium acetate
| verifiedrevid = 477003809
| ImageFile = Sodium-acetate-2D-skeletal.png
| Name = Sodium acetate
| ImageSize = 150px
| ImageName = Sodium acetate | ImageFile = Sodium-acetate-2D-skeletal.png
| IUPACName = Sodium acetate | ImageName = Skeletal formula of sodium acetate
| ImageSize = 150px
| ImageFileL1 = Acetate-anion-3D-balls.png
| ImageFile1 = Sodium-acetate-form-I-xtal-sheet-3D-bs-17.png
| ImageSizeL1 = 120px
| ImageSize1 =
| ImageNameL1 = Ball-and-stick model of the acetate anion
| ImageFile2 = Octan sodný.JPG
| ImageFileR1 = Sodium-3D.png
| ImageName2 = Sodium acetate
| ImageSizeR1 = 90px
| PIN = Sodium acetate
| ImageNameR1 = The sodium cation
| SystematicName = Sodium ethanoate
| ImageFile2 = Acetate de sodium hydraté.jpg
| OtherNames = Hot ice (sodium acetate trihydrate)
| SystematicName = Sodium ethanoate
|Section1={{Chembox Identifiers
| OtherNames = Hot ice (Sodium acetate trihydrate)
| index_label = anhydrous
| Section1 = {{Chembox Identifiers
| index1_label = trihydrate
| UNII_Ref = {{fdacite|correct|FDA}} | UNII_Ref = {{fdacite|correct|FDA}}
| UNII = NVG71ZZ7P0 | UNII = NVG71ZZ7P0
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = 4550K0SC9B
| ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1354 | ChEMBL = 1354
Line 24: Line 29:
| ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 32954 | ChEBI = 32954
| ChEBI1 = 32138
| DrugBank = DB09395
| KEGG1 = D01779
| SMILES = .C(=O)C | SMILES = .C(=O)C
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
Line 31: Line 39:
| CASNo_Ref = {{cascite|correct|CAS}} | CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 127-09-3 | CASNo = 127-09-3
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo1 = 6131-90-4 | CASNo1 = 6131-90-4
| CASNo1_Comment = (trihydrate)
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 29105 | ChemSpiderID = 29105
| PubChem = 517045 | PubChem = 517045
| PubChem1 = 23665404
| RTECS = AJ4300010 (anhydrous) <br> AJ4580000
| RTECS = AJ4300010&nbsp;(anhydrous)<br />AJ4580000
| ATCCode_prefix = B05
| EINECS = 204-823-8
| ATCCode_suffix = XA08
| Gmelin = 20502
| Beilstein = 3595639
}} }}
| Section2 = {{Chembox Properties |Section2={{Chembox Properties
| Na = 1 | C = 2| H = 3 | O = 2 | Na=1 | C=2 | H=3 | O=2
| Appearance = White deliquescent powder or crystals
| MolarMass = 82.0343 g/mol (anhydrous) <br> 136.0799 g/mol (trihydrate)
| Odor = Vinegar (acetic acid) odor when heated to decomposition<ref>{{cite web |url = https://www.cdc.gov/niosh/ipcsneng/neng0565.html |title = Sodium Acetate |work = International Chemical Safety Cards | publisher = National Institute of Occupational Safety and Health|date = 2018-09-18 }}</ref>
| Appearance = White deliquescent powder <br> odorless
| Density = 1.528 g/cm<sup>3</sup> <br> 1.45 g/cm<sup>3</sup> (trihydrate) | Density = 1.528 g/cm<sup>3</sup> (20 °C, anhydrous)<br/> 1.45 g/cm<sup>3</sup> (20 °C, trihydrate)<ref name=chemister2>{{cite web |url=http://chemister.ru/Database/properties-en.php?dbid=1&id=1510 |title=sodium acetate trihydrate |website=chemister.ru}}</ref>
| Solubility = Anhydrous:<br/> 119 g/100 mL (0 °C)<br/> 123.3 g/100 mL (20 °C)<br/> 125.5 g/100 mL (30 °C)<br/> 137.2 g/100 mL (60 °C)<br/> 162.9 g/100 mL (100 °C)<br/> Trihydrate:<br/> 32.9 g/100 mL (-10 °C)<br/> 36.2 g/100 mL (0 °C)<br/> 46.4 g/100 mL (20 °C)<br/> 82 g/100 mL (50 °C)<ref name=sioc>{{cite book |last1 = Seidell |first1 = Atherton |last2 = Linke |first2 = William F. |year = 1952 |title = Solubilities of Inorganic and Organic Compounds |publisher = Van Nostrand}}</ref>
| Solubility = 36.2 g/100 ml (0°C) <br> 46.4 g/100 mL (20°C) <br> 139 g/100 mL (60°C) <br> 170.15 g/100 mL (100°C)
| SolubleOther = soluble in ] (5.3 g/100 mL (trihydrate) | SolubleOther = Soluble in ], ], ]<ref name=chemister />
| Solubility1 = 16 g/100 g (15 °C)<br/> 16.55 g/100 g (67.7&nbsp;°C)<ref name=chemister />
| MeltingPt = 324 °C (anhydrous) <br> 58 °C (trihydrate)
| Solvent1 = methanol
| BoilingPt = 881.4 °C (anhydrous) <br> 122 °C (trihydrate)(decomposes)
| Solubility2 = Trihydrate:<br/> 5.3 g/100 mL
| pKb = 9.25
| Solvent2 = ethanol
| RefractIndex = 1.464
| Solubility3 = 0.5 g/kg (15 °C)<ref name=chemister>{{cite web |url=http://chemister.ru/Database/properties-en.php?dbid=1&id=172 |title=sodium acetate |website=chemister.ru}}</ref>
| Solvent3 = acetone
| MeltingPtC = 324
| MeltingPt_notes = <br/> (anhydrous)<br/> {{convert|58|C|F K}}<br/> (trihydrate)
| BoilingPtC = 881.4
| BoilingPt_notes = <br/> (anhydrous)<br/> {{convert|122|C|F K}}<br/> (trihydrate) decomposes
| pKb = 9.25
| RefractIndex = 1.464
| pKa = 24 (20 °C)<ref name=chemister /><br/> 4.75 (when mixed with ] as a buffer)<ref name="sigma">{{Sigma-Aldrich|id=229873|name=Sodium acetate|accessdate=2014-06-07}}</ref>
| MagSus = −37.6·10<sup>−6</sup> cm<sup>3</sup>/mol
}} }}
| Section3 = {{Chembox Structure |Section3={{Chembox Structure
| CrystalStruct = ] | CrystalStruct = ]
| Dipole = | Dipole =
}} }}
| Section7 = {{Chembox Hazards |Section5={{Chembox Thermochemistry
| DeltaHf = −709.32 kJ/mol (anhydrous)<ref name=chemister /><br/> −1604 kJ/mol (trihydrate)<ref name=chemister2 />
| ExternalMSDS =
| DeltaGf = −607.7 kJ/mol (anhydrous)<ref name=chemister />
| MainHazards = Irritant
| Entropy = 138.1 J/(mol·K) (anhydrous)<ref name=nist>{{nist|name=Acetic acid, sodium salt|id=C127093|accessdate=2014-05-25|mask=FFFF|units=SI}}.</ref><br/> 262 J/(mol·K) (trihydrate)<ref name=chemister2 />
| NFPA-H = 1
| HeatCapacity = 100.83 J/(mol·K) (anhydrous)<ref name=nist /><br/> 229 J/(mol·K) (trihydrate)<ref name=nist2>{{nist|name=Acetic acid, sodium salt, hydrate (1:1:3)|id=C6131904|accessdate=2014-05-25|mask=FFFF|units=SI}}.</ref>
}}
|Section6={{Chembox Pharmacology
| ATCCode_prefix = B05
| ATCCode_suffix = XA08
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards = Irritant
| NFPA-H = 0
| NFPA-F = 1 | NFPA-F = 1
| NFPA-R = 0 | NFPA-R = 1
| NFPA-O = | NFPA-S =
| FlashPt = 250 °C | FlashPt = >{{convert|250|C|F K}}
| FlashPt_ref = <ref name="sigma" />
| Autoignition = 607 °C
| AutoignitionPtC = 607
| AutoignitionPt_ref = <ref name="sigma" />
| LD50 = 3530 mg/kg (oral, rat)<br/> >10000 mg/kg (rabbit, dermal)
| LC50 = >30 g/m<sup>3</sup> (rat, 1&nbsp;h)
}} }}
| Section8 = {{Chembox Related |Section8={{Chembox Related
| OtherAnions = ]<br/>] | OtherAnions = ]<br/> ]
| OtherCations = ]<br/>] | OtherCations = ]<br/> ]
| OtherCompounds = ]
}} }}
}} }}


'''Sodium acetate''', '''CH<sub>3</sub>COO<sup></sup>Na''', also abbreviated NaOAc,<ref>{{Clayden}}</ref> also '''sodium ethanoate''', is the ] ] of ]. This colourless salt has a wide range of uses. '''Sodium acetate''', CH<sub>3</sub>COONa, also abbreviated ]]],<ref>{{Clayden}}</ref> is the ] ] of ]. This salt is colorless ], and ].


==Applications== ==Applications==

===Biotechnological===
Sodium acetate is used as the ] source for culturing ]. Sodium acetate can also be useful for increasing yields of ].

===Industrial=== ===Industrial===
Sodium acetate is used in the ] industry to neutralize ] waste streams, and as a ] while using ]. It is also a ] agent in chrome ], and it helps to retard ] of ] in ] production. Sodium acetate is used in the ] industry to neutralize ] waste streams and also as a ] while using ]. It is also a ] agent in chrome ] and helps to impede ] of ] in ] production. It is also used to reduce static electricity during production of disposable cotton pads.


===Concrete longevity=== ===Concrete longevity===
Sodium acetate is used to reduce the damage water can potentially do to concrete by acting as a ] ], while also being environmentally benign and cheaper than the ] alternative that is usually employed for sealing concrete against water ] Sodium acetate is used to mitigate water damage to concrete by acting as a ] ], while also being environmentally benign and cheaper than the commonly used ] alternative for sealing concrete against water ].<ref>{{cite news |url=https://www.sciencedaily.com/releases/2007/08/070806101941.htm |title=Potato Chip Flavoring Boosts Longevity Of Concrete |date=8 August 2007 |work=]}}</ref>
.<ref>http://www.sciencedaily.com/releases/2007/08/070806101941.htm</ref>


===Food=== ===Food===
Sodium acetate (anhydrous) is widely used as a shelf-life extending agent and pH-control agent.<ref>{{cite web |title=Food Additive "Sodium Acetate (Anhydrous)" |url=https://www.m-chemical.co.jp/en/products/departments/mcc/emulsifier/product/1206177_8006.html |website=Mitsubishi Chemical Corporation |access-date=16 September 2020 |language=en}}</ref> It is safe to eat at low concentration.<ref>{{cite journal |last1=Mohammadzadeh-Aghdash |first1=Hossein |last2=Sohrabi |first2=Yousef |last3=Mohammadi |first3=Ali |last4=Shanehbandi |first4=Dariush |last5=Dehghan |first5=Parvin |last6=Ezzati Nazhad Dolatabadi |first6=Jafar |title=Safety assessment of sodium acetate, sodium diacetate and potassium sorbate food additives |journal=Food Chemistry |date=15 August 2018 |volume=257 |pages=211–215 |doi=10.1016/j.foodchem.2018.03.020 |pmid=29622200 |s2cid=4596295 |url=https://www.sciencedirect.com/science/article/pii/S0308814618304370 |access-date=16 September 2020 |language=en |issn=0308-8146}}</ref>
Sodium acetate may be added to foods as a seasoning. It may be used in the form of ] &mdash; a 1:1 complex of sodium acetate and acetic acid,<ref>http://www.jungbunzlauer.com/products-applications/products/specialties/sodium-diacetate/general-information.html</ref> given the ] '''E262'''. A frequent use of this form is in ] chips in the ]. Many US brands, including national manufacturer ], sell "salt and vinegar ''flavoured''" chips that use this chemical, with lactose and smaller percentages of other chemicals, in lieu of a real salt and vinegar preparation.<ref>http://www.fritolay.com/our-snacks/lays-salt-vinegar.html</ref>


===Buffer solution=== ===Buffer solution===
As the conjugate base of a weak acid, a solution of sodium acetate and acetic acid can act as a ] to keep a relatively constant pH. This is useful especially in biochemical applications where reactions are pH dependent. A solution of sodium acetate (a basic salt of acetic acid) and acetic acid can act as a ] to keep a relatively constant pH level. This is useful especially in biochemical applications where reactions are pH-dependent in a mildly acidic range (pH 4–6).


===Heating pad=== ===Heating pad===
] contains a ] of sodium acetate which releases heat upon ]]]
Sodium acetate is also used in consumer ]s or ]s and is also used in hot ice. Sodium acetate trihydrate crystals melt at 54°C,<ref name="Température"></ref> (to 58°C <ref name=IDMA/>) dissolving in their ]. When they are heated to around 100°C, and subsequently allowed to cool, the aqueous solution becomes ]. This solution is capable of cooling to room temperature without forming crystals. By clicking on a metal disc in the heating pad, a ] centre is formed which causes the solution to crystallize into solid sodium acetate trihydrate again. The bond-forming process of crystallization is ].<ref>{{cite web | publisher = ] | url = http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/ACETATE/PAGE1.HTM | title = Crystallization of Supersaturated Sodium Acetate}}</ref><ref></ref><ref>{{cite web | title = How do sodium acetate heat pads work? | publisher = ] | accessdate = 2007-09-03 | url = http://www.howstuffworks.com/question290.htm}}</ref> The ] is about 264–289 kJ/kg.<ref name=IDMA>Ibrahim Dincer and Marc A. Rosen. , page 155</ref> Unlike some other types of heat packs that depend on irreversible chemical reactions, sodium acetate heat packs can be easily recharged by placing in boiling water for a few minutes until all crystals are dissolved; they can be reused many times.
Sodium acetate is also used in ]s, ]s, and hot ice. A ] solution of sodium acetate in water is supplied with a device to initiate crystallization, a process that releases substantial heat.


]
] ] containing a ] of sodium acetate which releases heat on ]]]
Sodium acetate trihydrate crystals melt at {{Convert|58-58.4|°C|°F}},<ref name="IDMA" /><ref name="Température">{{cite web |author=Courty J.-M., Kierlik É. |title=Les chaufferettes chimiques |lang=fr |work=Pour la Science |date=2008-12-01 |pages=108–110 |url=https://www.pourlascience.fr/sd/physique/les-chaufferettes-chimiques-892.php}}</ref> and the liquid sodium acetate dissolves in the released ]. When heated past the melting point and subsequently allowed to cool, the aqueous solution becomes ]. This solution is capable of cooling to room temperature without forming crystals. By pressing on a metal disc within the heating pad, a ] center is formed, causing the solution to crystallize back into solid sodium acetate trihydrate. The process of crystallization is ].<ref>{{cite web | publisher = ] | url = http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/ACETATE/PAGE1.HTM | title = Crystallization of Supersaturated Sodium Acetate| date = 2015-07-19 }}</ref> The ] is about 264–289&nbsp;kJ/kg.<ref name=IDMA>Ibrahim Dincer and Marc A. Rosen. , page 155.</ref> Unlike some types of heat packs, such as those dependent upon irreversible chemical reactions, a sodium acetate heat pack can be easily reused by immersing the pack in boiling water for a few minutes, until the crystals are completely dissolved, and allowing the pack to slowly cool to room temperature.<ref>{{cite web | title = How do sodium acetate heat pads work? | publisher = ] | access-date = 2007-09-03 | url = http://www.howstuffworks.com/question290.htm| date = April 2000 }}</ref>


==Preparation== ==Preparation==
{{Unreferenced section|date=November 2023}}
]
]
For laboratory use, sodium acetate is very inexpensive, and is usually purchased instead of being synthesized. It is sometimes produced in a laboratory experiment by the reaction of ] (also called ]) with ], ], or ]. These reactions produce aqueous sodium acetate and water. Carbon dioxide is produced in the reaction with sodium carbonate and bicarbonate, and it leaves the reaction vessel as a gas (unless the reaction vessel is pressurized). This is the well-known "volcano" reaction between ] and ].
For laboratory use, sodium acetate is inexpensive and usually purchased instead of being synthesized. It is sometimes produced in a laboratory experiment by the reaction of ], commonly in the 5–18% solution known as ], with ] ("washing soda"), ] ("baking soda"), or ] ("lye", or "caustic soda"). Any of these reactions produce sodium acetate and water. When a sodium and carbonate ion-containing compound is used as the reactant, the carbonate anion from sodium bicarbonate or carbonate, reacts with the hydrogen from the carboxyl group (-COOH) in acetic acid, forming ]. Carbonic acid readily decomposes under normal conditions into gaseous carbon dioxide and water. This is the reaction taking place in the well-known "volcano" that occurs when the household products, baking soda and vinegar, are combined.
:CH<sub>3</sub>COOH + NaHCO<sub>3</sub> → CH<sub>3</sub>COONa + {{chem|H<sub>2</sub>CO|3}}
:{{chem|H<sub>2</sub>CO|3}} → {{chem|CO|2}} + {{chem|H|2|O}}


Industrially, sodium acetate trihydrate is prepared by reacting ] with ] using ] as the ].
:CH<sub>3</sub>COOH + NaHCO<sub>3</sub> → CH<sub>3</sub>COO<sup></sup>Na + H<sub>2</sub>O + CO<sub>2</sup>
:CH<sub>3</sub>COOH + NaOH → CH<sub>3</sub>COONa + H<sub>2</sub>O.


To manufacture anhydrous sodium acetate industrially, the Niacet Process is used. Sodium metal ingots are extruded through a die to form a ribbon of ] metal, usually under an inert gas atmosphere such as N<sub>2</sub> then immersed in anhydrous ].
Industrially, sodium acetate is prepared from ] and ].
:CH<sub>3</sub>COOH + NaOH → CH<sub>3</sub>COO<sup></sup>Na + H<sub>2</sub>O :2 CH<sub>3</sub>COOH + 2 Na →2 CH<sub>3</sub>COONa + H<sub>2</sub>.

The ] gas is normally a valuable byproduct.

==Structure==
The ] of ] sodium acetate has been described as alternating sodium-carboxylate and ] layers.<ref name="Hsu&Nordman">{{ cite journal | journal = ] | year = 1983 | volume = 39 | pages = 690–694 | first1 = Leh-Yeh | last1 = Hsu | first2 = C. E. | last2 = Nordman | title = Structures of two forms of sodium acetate, Na<sup>+</sup>.C<sub>2</sub>H<sub>3</sub>O<sub>2</sub><sup>&minus;</sup> | issue = 6 | doi = 10.1107/S0108270183005946 | bibcode = 1983AcCrC..39..690H }}</ref> Sodium acetate ]'s structure consists of distorted octahedral coordination at sodium. Adjacent octahedra share edges to form one-dimensional chains. ] in two dimensions between acetate ions and ] links the chains into a three-dimensional network.<ref name="CameronMannanRahman">{{ cite journal | journal = ] | year = 1976 | volume = 32 | pages = 87–90 | first1 = T. S. | last1 = Cameron | first2 = K. M. | last2 = Mannan | first3 = M. O. | last3 = Rahman | title = The crystal structure of sodium acetate trihydrate | issue = 1 | doi = 10.1107/S0567740876002367 | bibcode = 1976AcCrB..32...87C }}</ref><ref name="Wei&Ward">{{ cite journal | journal = ] | year = 1977 | volume = 33 | pages = 522–526 | first1 = K.-T. | last1 = Wei | first2 = D. L. | last2 = Ward | title = Sodium acetate trihydrate: a redetermination | issue = 2 | doi = 10.1107/S0567740877003975 | bibcode = 1977AcCrB..33..522W }}</ref>

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+Comparison of anhydrous and trihydrate crystal structures
|-
! Degree of hydration
! Anhydrous<ref name="Hsu&Nordman" />
! Trihydrate<ref name="CameronMannanRahman" /><ref name="Wei&Ward" />
|-
! Na coordination
| ]
| ]
|-
! Strongly bonded aggregation
| ]<br />2D sheet
| ]<br />1D chain
|-
! Weakly bonded aggregation
| ]<br />sheets stacked with<br />hydrophobic surfaces in contact
| ]<br />chains linked by hydrogen bonds<br />(one chain highlighted in light blue)
|-
|}


==Reactions== ==Reactions==
Sodium acetate can be used to form an ] with an alkyl halide such as ]: Sodium acetate can be used to form an ] with an alkyl halide such as ]:
: CH<sub>3</sub>COO<sup></sup>Na + BrCH<sub>2</sub>CH<sub>3</sub> → ] + ] : CH<sub>3</sub>COONa + BrCH<sub>2</sub>CH<sub>3</sub> → ] + ]

Caesium salts catalyze this reaction.
Sodium acetate undergoes decarboxylation to form methane (CH<sub>4</sub>) under forcing conditions (pyrolysis in the presence of sodium hydroxide):

: CH<sub>3</sub>COONa + NaOH → CH<sub>4</sub> + Na<sub>2</sub>CO<sub>3</sub>

Calcium oxide is the typical catalyst used for this reaction.
Cesium salts also catalyze this reaction.{{citation needed|date=January 2020}}


==References== ==References==
{{reflist}} {{Reflist}}


==External links== ==External links==
{{Commons category|Sodium acetate}}
* *
* *
*{{cite web|last=Lavars|first=Nick|date=2021-09-15|title=Sodium acetate acts as a potential fountain of youth for aging bones|url=https://newatlas.com/medical/sodium-acetate-potential-fountain-youth-aging-bones/|access-date=2021-09-16|website=New Atlas|language=en-US}}


{{Sodium compounds}} {{Sodium compounds}}

{{Acetates}}
{{Authority control}}


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Latest revision as of 13:20, 1 January 2025

Chemical compound "Hot ice" redirects here. For other uses, see Hot ice (disambiguation).
Sodium acetate
Skeletal formula of sodium acetate
Sodium acetate
Names
Preferred IUPAC name Sodium acetate
Systematic IUPAC name Sodium ethanoate
Other names Hot ice (sodium acetate trihydrate)
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 3595639
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.004.386 Edit this at Wikidata
EC Number
  • anhydrous: 204-823-8
E number E262 (preservatives)
Gmelin Reference 20502
KEGG
PubChem CID
RTECS number
  • anhydrous: AJ4300010 (anhydrous)
    AJ4580000
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C2H4O2.Na/c1-2(3)4;/h1H3,(H,3,4);/q;+1/p-1Key: VMHLLURERBWHNL-UHFFFAOYSA-M
  • anhydrous: InChI=1/C2H4O2.Na/c1-2(3)4;/h1H3,(H,3,4);/q;+1/p-1Key: VMHLLURERBWHNL-REWHXWOFAT
SMILES
  • anhydrous: .C(=O)C
Properties
Chemical formula C2H3NaO2
Molar mass 82.034 g·mol
Appearance White deliquescent powder or crystals
Odor Vinegar (acetic acid) odor when heated to decomposition
Density 1.528 g/cm (20 °C, anhydrous)
1.45 g/cm (20 °C, trihydrate)
Melting point 324 °C (615 °F; 597 K)
(anhydrous)
58 °C (136 °F; 331 K)
(trihydrate)
Boiling point 881.4 °C (1,618.5 °F; 1,154.5 K)
(anhydrous)
122 °C (252 °F; 395 K)
(trihydrate) decomposes
Solubility in water Anhydrous:
119 g/100 mL (0 °C)
123.3 g/100 mL (20 °C)
125.5 g/100 mL (30 °C)
137.2 g/100 mL (60 °C)
162.9 g/100 mL (100 °C)
Trihydrate:
32.9 g/100 mL (-10 °C)
36.2 g/100 mL (0 °C)
46.4 g/100 mL (20 °C)
82 g/100 mL (50 °C)
Solubility Soluble in alcohol, hydrazine, SO2
Solubility in methanol 16 g/100 g (15 °C)
16.55 g/100 g (67.7 °C)
Solubility in ethanol Trihydrate:
5.3 g/100 mL
Solubility in acetone 0.5 g/kg (15 °C)
Acidity (pKa) 24 (20 °C)
4.75 (when mixed with CH3COOH as a buffer)
Basicity (pKb) 9.25
Magnetic susceptibility (χ) −37.6·10 cm/mol
Refractive index (nD) 1.464
Structure
Crystal structure Monoclinic
Thermochemistry
Heat capacity (C) 100.83 J/(mol·K) (anhydrous)
229 J/(mol·K) (trihydrate)
Std molar
entropy (S298) 		138.1 J/(mol·K) (anhydrous)
262 J/(mol·K) (trihydrate)
Std enthalpy of
formation (ΔfH298) 		−709.32 kJ/mol (anhydrous)
−1604 kJ/mol (trihydrate)
Gibbs free energy (ΔfG) −607.7 kJ/mol (anhydrous)
Pharmacology
ATC code B05XA08 (WHO)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Irritant
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
0 1 1
Flash point >250 °C (482 °F; 523 K)
Autoignition
temperature 		607 °C (1,125 °F; 880 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose) 3530 mg/kg (oral, rat)
>10000 mg/kg (rabbit, dermal)
LC50 (median concentration) >30 g/m (rat, 1 h)
Safety data sheet (SDS) Fisher Scientific
Related compounds
Other anions Sodium formate
Sodium propionate
Other cations Potassium acetate
Calcium acetate
Related compounds Sodium diacetate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

Sodium acetate, CH3COONa, also abbreviated NaOAc, is the sodium salt of acetic acid. This salt is colorless deliquescent, and hygroscopic.

Applications

Biotechnological

Sodium acetate is used as the carbon source for culturing bacteria. Sodium acetate can also be useful for increasing yields of DNA isolation by ethanol precipitation.

Industrial

Sodium acetate is used in the textile industry to neutralize sulfuric acid waste streams and also as a photoresist while using aniline dyes. It is also a pickling agent in chrome tanning and helps to impede vulcanization of chloroprene in synthetic rubber production. It is also used to reduce static electricity during production of disposable cotton pads.

Concrete longevity

Sodium acetate is used to mitigate water damage to concrete by acting as a concrete sealant, while also being environmentally benign and cheaper than the commonly used epoxy alternative for sealing concrete against water permeation.

Food

Sodium acetate (anhydrous) is widely used as a shelf-life extending agent and pH-control agent. It is safe to eat at low concentration.

Buffer solution

A solution of sodium acetate (a basic salt of acetic acid) and acetic acid can act as a buffer to keep a relatively constant pH level. This is useful especially in biochemical applications where reactions are pH-dependent in a mildly acidic range (pH 4–6).

Heating pad

A hand warmer contains a supersaturated solution of sodium acetate which releases heat upon crystallization

Sodium acetate is also used in heating pads, hand warmers, and hot ice. A supersaturated solution of sodium acetate in water is supplied with a device to initiate crystallization, a process that releases substantial heat.

Solubility from CRC Handbook

Sodium acetate trihydrate crystals melt at 58–58.4 °C (136.4–137.1 °F), and the liquid sodium acetate dissolves in the released water of crystallization. When heated past the melting point and subsequently allowed to cool, the aqueous solution becomes supersaturated. This solution is capable of cooling to room temperature without forming crystals. By pressing on a metal disc within the heating pad, a nucleation center is formed, causing the solution to crystallize back into solid sodium acetate trihydrate. The process of crystallization is exothermic. The latent heat of fusion is about 264–289 kJ/kg. Unlike some types of heat packs, such as those dependent upon irreversible chemical reactions, a sodium acetate heat pack can be easily reused by immersing the pack in boiling water for a few minutes, until the crystals are completely dissolved, and allowing the pack to slowly cool to room temperature.

Preparation

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A crystal of sodium acetate trihydrate (length 1.7 centimetres)

For laboratory use, sodium acetate is inexpensive and usually purchased instead of being synthesized. It is sometimes produced in a laboratory experiment by the reaction of acetic acid, commonly in the 5–18% solution known as vinegar, with sodium carbonate ("washing soda"), sodium bicarbonate ("baking soda"), or sodium hydroxide ("lye", or "caustic soda"). Any of these reactions produce sodium acetate and water. When a sodium and carbonate ion-containing compound is used as the reactant, the carbonate anion from sodium bicarbonate or carbonate, reacts with the hydrogen from the carboxyl group (-COOH) in acetic acid, forming carbonic acid. Carbonic acid readily decomposes under normal conditions into gaseous carbon dioxide and water. This is the reaction taking place in the well-known "volcano" that occurs when the household products, baking soda and vinegar, are combined.

CH3COOH + NaHCO3 → CH3COONa + H2CO
3
H2CO
3 → CO
2 + H
2O

Industrially, sodium acetate trihydrate is prepared by reacting acetic acid with sodium hydroxide using water as the solvent.

CH3COOH + NaOH → CH3COONa + H2O.

To manufacture anhydrous sodium acetate industrially, the Niacet Process is used. Sodium metal ingots are extruded through a die to form a ribbon of sodium metal, usually under an inert gas atmosphere such as N2 then immersed in anhydrous acetic acid.

2 CH3COOH + 2 Na →2 CH3COONa + H2.

The hydrogen gas is normally a valuable byproduct.

Structure

The crystal structure of anhydrous sodium acetate has been described as alternating sodium-carboxylate and methyl group layers. Sodium acetate trihydrate's structure consists of distorted octahedral coordination at sodium. Adjacent octahedra share edges to form one-dimensional chains. Hydrogen bonding in two dimensions between acetate ions and water of hydration links the chains into a three-dimensional network.

Comparison of anhydrous and trihydrate crystal structures
Degree of hydration Anhydrous Trihydrate
Na coordination
Strongly bonded aggregation
2D sheet
1D chain
Weakly bonded aggregation
sheets stacked with
hydrophobic surfaces in contact
chains linked by hydrogen bonds
(one chain highlighted in light blue)

Reactions

Sodium acetate can be used to form an ester with an alkyl halide such as bromoethane:

CH3COONa + BrCH2CH3 → CH3COOCH2CH3 + NaBr

Sodium acetate undergoes decarboxylation to form methane (CH4) under forcing conditions (pyrolysis in the presence of sodium hydroxide):

CH3COONa + NaOH → CH4 + Na2CO3

Calcium oxide is the typical catalyst used for this reaction. Cesium salts also catalyze this reaction.

References

  1. "Sodium Acetate". International Chemical Safety Cards. National Institute of Occupational Safety and Health. 2018-09-18.
  2. ^ "sodium acetate trihydrate". chemister.ru.
  3. Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand.
  4. ^ "sodium acetate". chemister.ru.
  5. ^ Sigma-Aldrich Co., Sodium acetate. Retrieved on 2014-06-07.
  6. ^ Acetic acid, sodium salt in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-25).
  7. Acetic acid, sodium salt, hydrate (1:1:3) in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-25).
  8. Clayden, Jonathan; Greeves, Nick; Warren, Stuart; Wothers, Peter (2001). Organic Chemistry (1st ed.). Oxford University Press. ISBN 978-0-19-850346-0.
  9. "Potato Chip Flavoring Boosts Longevity Of Concrete". Science Daily. 8 August 2007.
  10. "Food Additive "Sodium Acetate (Anhydrous)"". Mitsubishi Chemical Corporation. Retrieved 16 September 2020.
  11. Mohammadzadeh-Aghdash, Hossein; Sohrabi, Yousef; Mohammadi, Ali; Shanehbandi, Dariush; Dehghan, Parvin; Ezzati Nazhad Dolatabadi, Jafar (15 August 2018). "Safety assessment of sodium acetate, sodium diacetate and potassium sorbate food additives". Food Chemistry. 257: 211–215. doi:10.1016/j.foodchem.2018.03.020. ISSN 0308-8146. PMID 29622200. S2CID 4596295. Retrieved 16 September 2020.
  12. ^ Ibrahim Dincer and Marc A. Rosen. Thermal Energy Storage: Systems and Applications, page 155.
  13. Courty J.-M., Kierlik É. (2008-12-01). "Les chaufferettes chimiques". Pour la Science (in French). pp. 108–110.
  14. "Crystallization of Supersaturated Sodium Acetate". Journal of Chemical Education. 2015-07-19.
  15. "How do sodium acetate heat pads work?". HowStuffWorks. April 2000. Retrieved 2007-09-03.
  16. ^ Hsu, Leh-Yeh; Nordman, C. E. (1983). "Structures of two forms of sodium acetate, Na.C2H3O2". Acta Crystallogr. C. 39 (6): 690–694. Bibcode:1983AcCrC..39..690H. doi:10.1107/S0108270183005946.
  17. ^ Cameron, T. S.; Mannan, K. M.; Rahman, M. O. (1976). "The crystal structure of sodium acetate trihydrate". Acta Crystallogr. B. 32 (1): 87–90. Bibcode:1976AcCrB..32...87C. doi:10.1107/S0567740876002367.
  18. ^ Wei, K.-T.; Ward, D. L. (1977). "Sodium acetate trihydrate: a redetermination". Acta Crystallogr. B. 33 (2): 522–526. Bibcode:1977AcCrB..33..522W. doi:10.1107/S0567740877003975.

External links

Sodium compounds
Inorganic
Halides
Chalcogenides
Pnictogenides
Oxyhalides
Oxychalcogenides
Oxypnictogenides
Others
Organic
Acetyl halides and salts of the acetate ion
AcOH He
LiOAc Be(OAc)2
Be4O(OAc)6 		B(OAc)3
B2O(OAc)4 		AcOAc
ROAc 		NH4OAc AcOOH FAc
FOAc 		Ne
NaOAc
NaH(OAc)2 		Mg(OAc)2 Al(OAc)3
ALSOL
Al(OAc)2OH
Al(OH)2OAc
Al2SO4(OAc)4 		Si P S ClAc
ClOAc 		Ar
KOAc Ca(OAc)2 Sc(OAc)3 Ti(OAc)4 VO(OAc)3 Cr(OAc)2
Cr(OAc)3 		Mn(OAc)2
Mn(OAc)3 		Fe(OAc)2
Fe(OAc)3 		Co(OAc)2 Ni(OAc)2 CuOAc
Cu(OAc)2 		Zn(OAc)2 Ga(OAc)3 Ge As(OAc)3 Se BrAc
BrOAc 		Kr
RbOAc Sr(OAc)2 Y(OAc)3 Zr(OAc)4 Nb Mo(OAc)2 Tc Ru2(OAc)4Cl
Ru(OAc)3 		Rh2(OAc)4 Pd(OAc)2 AgOAc Cd(OAc)2 In(OAc)3 Sn(OAc)2
Sn(OAc)4 		Sb(OAc)3 Te IAc
IOAc
I(OAc)3 		Xe
CsOAc Ba(OAc)2 * Lu(OAc)3 Hf Ta W Re Os Ir Pt(OAc)2 Au(OAc)3 Hg2(OAc)2
Hg(OAc)2 		TlOAc
Tl(OAc)3 		Pb(OAc)2
Pb(OAc)4 		Bi(OAc)3 Po At Rn
Fr Ra ** Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
 
* La(OAc)3 Ce(OAc)3 Pr(OAc)3 Nd(OAc)3 Pm Sm(OAc)3 Eu(OAc)3 Gd(OAc)3 Tb(OAc)3 Dy(OAc)3 Ho(OAc)3 Er(OAc)3 Tm(OAc)3 Yb(OAc)3
** Ac(OAc)3 Th(OAc)4 Pa UO2(OAc)2 Np Pu Am Cm Bk Cf Es Fm Md No
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