Sodium Acetate - Wikipedia

Chemical compound "Hot ice" redirects here. For other uses, see Hot ice (disambiguation). Sodium acetate

Names
Preferred IUPAC name Sodium acetate
Systematic IUPAC name Sodium ethanoate
Other names Hot ice (sodium acetate trihydrate)
Identifiers
CAS Number	anhydrous: 127-09-3 Y trihydrate: 6131-90-4 Y
3D model (JSmol)	anhydrous: Interactive image
Beilstein Reference	3595639
ChEBI	anhydrous: CHEBI:32954 Y trihydrate: CHEBI:32138
ChEMBL	anhydrous: ChEMBL1354 Y
ChemSpider	anhydrous: 29105 Y
DrugBank	anhydrous: DB09395
ECHA InfoCard	100.004.386
EC Number	anhydrous: 204-823-8
E number	E262 (preservatives)
Gmelin Reference	20502
KEGG	trihydrate: D01779
PubChem CID	anhydrous: 517045 trihydrate: 23665404
RTECS number	anhydrous: AJ4300010 (anhydrous)AJ4580000
UNII	anhydrous: NVG71ZZ7P0 Y trihydrate: 4550K0SC9B Y
CompTox Dashboard (EPA)	anhydrous: DTXSID2027044
InChI InChI=1S/C2H4O2.Na/c1-2(3)4;/h1H3,(H,3,4);/q;+1/p-1 YKey: VMHLLURERBWHNL-UHFFFAOYSA-M Y anhydrous: InChI=1/C2H4O2.Na/c1-2(3)4;/h1H3,(H,3,4);/q;+1/p-1Key: VMHLLURERBWHNL-REWHXWOFAT
SMILES anhydrous: [Na+].[O-]C(=O)C
Properties
Chemical formula	C2H3NaO2
Molar mass	82.034 g·mol−1
Appearance	White deliquescent powder or crystals
Odor	Vinegar (acetic acid) odor when heated to decomposition[1]
Density	1.528 g/cm3 (20 °C, anhydrous) 1.45 g/cm3 (20 °C, trihydrate)[2]
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)[3]
Solubility	Soluble in alcohol, hydrazine, SO2[4]
Solubility in methanol	16 g/100 g (15 °C) 16.55 g/100 g (67.7 °C)[4]
Solubility in ethanol	Trihydrate: 5.3 g/100 mL
Solubility in acetone	0.5 g/kg (15 °C)[4]
Acidity (pKa)	24 (20 °C)[4] 4.75 (when mixed with CH3COOH as a buffer)[5]
Basicity (pKb)	9.25
Magnetic susceptibility (χ)	−37.6·10−6 cm3/mol
Refractive index (nD)	1.464
Structure
Crystal structure	Monoclinic
Thermochemistry
Heat capacity (C)	100.83 J/(mol·K) (anhydrous)[6] 229 J/(mol·K) (trihydrate)[7]
Std molarentropy (S⦵298)	138.1 J/(mol·K) (anhydrous)[6] 262 J/(mol·K) (trihydrate)[2]
Std enthalpy offormation (ΔfH⦵298)	−709.32 kJ/mol (anhydrous)[4] −1604 kJ/mol (trihydrate)[2]
Gibbs free energy (ΔfG⦵)	−607.7 kJ/mol (anhydrous)[4]
Pharmacology
ATC code	B05XA08 (WHO)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritant
NFPA 704 (fire diamond)	0 1 1
Flash point	>250 °C (482 °F; 523 K)[5]
Autoignitiontemperature	607 °C (1,125 °F; 880 K)[5]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	3530 mg/kg (oral, rat) >10000 mg/kg (rabbit, dermal)
LC50 (median concentration)	>30 g/m3 (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 [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

Sodium acetate, CH3COONa, also abbreviated NaOAc,[8] is the sodium salt of acetic acid. This salt is colorless, deliquescent, and hygroscopic.

Applications

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Biotechnological

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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

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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

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Sodium acetate is used as a sealant to mitigate water damage to concrete. It is environmentally benign and cheaper than the commonly used epoxy alternative for sealing concrete against water permeation.[9]

Food

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Sodium acetate (anhydrous) is widely used as a shelf-life extending agent and pH control agent.[10] It is safe to eat at low concentration.[11]

Buffer solution

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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

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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.

Sodium acetate trihydrate crystals melt at 58–58.4 °C (136.4–137.1 °F),[12][13] 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.[14] The latent heat of fusion is about 264–289 kJ/kg.[12] 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.[15]

Heat stores and batteries

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Sodium acetate trihydrate can also be used as a phase-change material to store heat, especially to provide domestic hot water for heat pump applications. The heat store consists of a well-insulated container filled with the salt through which pass a pair of copper coils. One coil is used to melt the material by passing hot water from either solar thermal panels or a heat pump. Cold mains water passes through the other coil where its temperature is raised to 40 or 50 ˚C to provide water for washing or cleaning. This process can be cycled almost indefinitely.

Preparation

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Source:[16]

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"). When sodium bicarbonate is used the reaction between the bicarbonate ion and acetic acid forms carbonic acid which 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 + H2CO3 H2CO3 → CO2 + H2O

Industrially, hydrated sodium acetate is prepared by reacting acetic acid with sodium hydroxide using water as the solvent.[17]

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, and then immersed in anhydrous acetic acid.

2 CH3COOH + 2 Na →2 CH3COONa + H2.

The hydrogen gas is normally a valuable byproduct.

Structure

[edit]

The crystal structure of anhydrous sodium acetate has been described as alternating sodium-carboxylate and methyl group layers.[18] 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.[19][20]

Comparison of anhydrous and trihydrate crystal structures

Degree of hydration	Anhydrous[18]	Trihydrate[19][20]
Na coordination
Strongly bonded aggregation	2D sheet	1D chain
Weakly bonded aggregation	sheets stacked withhydrophobic surfaces in contact	chains linked by hydrogen bonds(one chain highlighted in light blue)

Reactions

[edit]

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. Caesium salts also catalyze this reaction.[citation needed]

References

[edit]

1. ^ "Sodium Acetate". International Chemical Safety Cards. National Institute of Occupational Safety and Health. 2018-09-18.
2. ^ a b c "sodium acetate trihydrate". chemister.ru.
3. ^ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand.
4. ^ a b c d e f "sodium acetate". chemister.ru.
5. ^ a b c Sigma-Aldrich Co., Sodium acetate. Retrieved on 2014-06-07.
6. ^ a b 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. ^ a b 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. ^ "Sodium Acetate: Sodium Acetate, Anhydrous", ACS Reagent Chemicals, Washington, DC: American Chemical Society, January 2017, doi:10.1021/acsreagents.4326, ISBN 978-0-8412-3046-0, retrieved 2025-10-30
17. ^ Wiley-VCH, ed. (2003-03-11). Ullmann's Encyclopedia of Industrial Chemistry (1 ed.). Wiley. doi:10.1002/14356007.a01_045.pub3. ISBN 978-3-527-30385-4.
18. ^ a b 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.
19. ^ a b 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.
20. ^ a b 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

[edit] Wikimedia Commons has media related to Sodium acetate.

• Hot Ice – Instructions, Pictures, and Videos
• How Sodium Acetate heating pads work
• Lavars, Nick (2021-09-15). "Sodium acetate acts as a potential fountain of youth for aging bones". New Atlas. Retrieved 2021-09-16.

v t e Sodium compounds
Inorganic	Halides NaF NaHF2 NaCl NaBr NaI NaAt Chalcogenides NaO3 NaO2 Na2O Na2O2 NaOH NaOD Na2S NaSH Na2Se NaSeH Na2Te NaHTe Na2Po Pnictogenides Na3N NaN3 NaNH2 NaN2H3 Na3P Na3As Na3Sb Oxyhalides NaClO NaClO2 NaClO3 NaClO4 NaBrO NaBrO2 NaBrO3 NaBrO4 NaIO NaIO3 NaIO4 Oxychalcogenides Na2SO3 Na2SO4 NaHSO3 NaHSO4 Na2S2O3 Na2S2O4 Na2S2O5 Na2S2O6 Na2S2O7 Na2S2O8 Na2S4O6 Na2SeO3 Na2SeO4 NaHSeO3 Na2TeO3 Oxypnictogenides NaNO2 NaNO3 Na2N2O2 Na2N2O3 NaH2PO4 NaPO3 Na2HPO4 NaPO2H2 Na2HPO3 Na2PO3F Na3PS2O2 Na3PO4 Na5P3O10 Na4P2O7 Na2H2P2O7 Na3AsO3 Na3AsO4 Na2HAsO4 NaH2AsO4 NaSbO3 Metalates NaAlH4 NaAlO2 Na3AlF6 NaAl(SO4)2 NaAuCl4 Na2TiF6 NaBiO3 NaCoO2 NaMnO4 NaReO4 NaTcO3 NaTcO4 NaVO3 Na2CrO4 Na2Cr2O7 Na2Cr3O10 Na2[Fe(CO)4] Na2MnO4 Na2MoO4 Na3IrCl6 Na2PtCl6 Na2TiO3 Na2U2O7 Na2WO4 Na2Zn(OH)4 Na3VO4 Na6V10O28 Na4Fe(CN)6 Na3Fe(CN)6 Na3Fe(C2O4)3 Na3[Co(NO2)6] Na2PdCl4 Others NaSbF6 NaAsF6 NaBH4 NaBH3(CN) NaBO2 Na2B4O7 Na2B2O9 Na2B8O13 NaCN NaCNO NaH NaHCO3 Na4XeO6 NaHXeO4 NaOCN NaSCN Na2CO3 Na2C2O4 Na2C3S5 Na2GeO3 Na2He Na2xSi3yO2y+x (Na2SiO3 Na6Si2O7 Na4SiO4) Na2SiF6 NaNSi2(CH3)6
Organic	CH3ONa C2H5ONa HCOONa C2H5COONa C3H7COONa Na2C4H4O6 C4H5NaO6 NaCH3COO NaC6H5CO2 NaC6H4(OH)CO2 NaC12H23O2 NaC10H8 Na2[Fe[CN5]NO] C6H16AlNaO4 NaC6H7O6 C5H8NO4Na C6H5Na C4H9Na NaC5H5 C15H31COONa C17H33COONa C18H35O2Na C164H256O68S2Na2

v t e Acetyl halides and salts of the acetate ion

AcOH He LiOAc Be(OAc)2Be4O(OAc)6 B(OAc)3B2O(OAc)4 AcOAcROAc NH4OAc AcOOH FAcFOAc Ne NaOAcNaH(OAc)2 Mg(OAc)2 Al(OAc)3"ALSOL"Al(OAc)2OHAl(OH)2OAcAl2SO4(OAc)4 Si P S ClAcClOAc Ar KOAc Ca(OAc)2 Sc(OAc)3 Ti(OAc)4 VO(OAc)2 Cr(OAc)2Cr(OAc)3 Mn(OAc)2Mn(OAc)3 Fe(OAc)2Fe(OAc)3 Co(OAc)2 [CoO(OAc)py]4 Ni(OAc)2 CuOAcCu(OAc)2 Zn(OAc)2 Ga(OAc)3 Ge As(OAc)3 Se BrAcBrOAc Kr RbOAc Sr(OAc)2 Y(OAc)3 Zr(OAc)4 Nb Mo(OAc)2 Tc Ru2(OAc)4ClRu(OAc)3 Rh2(OAc)4 Pd(OAc)2 AgOAc Cd(OAc)2 In(OAc)3 Sn(OAc)2Sn(OAc)4 Sb(OAc)3 Te IAcIOAcI(OAc)3 Xe CsOAc Ba(OAc)2 * Lu(OAc)3 Hf Ta W Re Os Ir Pt(OAc)2 Au(OAc)3 Hg2(OAc)2Hg(OAc)2 TlOAcTl(OAc)3 Pb(OAc)2Pb(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 U(OAc)4 UO2(OAc)2 NpO2OAcNpO2(OAc)2 PuO2(OAc)2 Am Cm Bk Cf Es Fm Md No

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