Sodium acetate

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.

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.

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.{{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=Science Daily}}

Sodium acetate (anhydrous) is widely used as a shelf-life extending agent and pH-control agent.{{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}} It is safe to eat at low concentration.{{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|url-access=subscription }}

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).

Image:Hand warmer.jpg 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.

File:Solubilite NaC2H3O2.png

Sodium acetate trihydrate crystals melt at {{Convert|58-58.4|°C|°F}},{{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}} 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.{{cite web | publisher = Journal of Chemical Education | url = http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/ACETATE/PAGE1.HTM | title = Crystallization of Supersaturated Sodium Acetate| date = 2015-07-19 }} The latent heat of fusion is about 264–289 kJ/kg.Ibrahim Dincer and Marc A. Rosen. [https://books.google.com/books?id=EsfcWE5lX40C&q=latent+heat+of+fusion+sodium+acetate#search Thermal Energy Storage: Systems and Applications], page 155. 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.{{cite web | title = How do sodium acetate heat pads work? | publisher = HowStuffWorks | access-date = 2007-09-03 | url = http://www.howstuffworks.com/question290.htm| date = April 2000 }}

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.

{{Unreferenced section|date=November 2023}}

Image:Sodium acetate trihydrate crystal - 2009-01-28.jpg

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 or sodium acetate and carbonic acid. 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 + {{chem|H₂CO|3}}

:{{chem|H₂CO|3}} → {{chem|CO|2}} + {{chem|H|2|O}}

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.

The crystal structure of anhydrous sodium acetate has been described as alternating sodium-carboxylate and methyl group layers.{{ cite journal | journal = Acta Crystallogr. C | 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⁺.C₂H₃O₂⁻ | issue = 6 | doi = 10.1107/S0108270183005946 | bibcode = 1983AcCrC..39..690H }} 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.{{ cite journal | journal = Acta Crystallogr. B | 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 }}{{ cite journal | journal = Acta Crystallogr. B | 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 }}

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.{{citation needed|date=January 2020}}

{{Reflist}}

{{Commons category|Sodium acetate}}

• [http://www.amazingrust.com/Experiments/how_to/Hot-Ice.html Hot Ice – Instructions, Pictures, and Videos]
• [https://www.youtube.com/watch?v=C87MnA1PQP0 How Sodium Acetate heating pads work]
• {{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}}

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