出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2016/01/30 06:47:39」(JST)
Names | |
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IUPAC name
Sodium acetate
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Systematic IUPAC name
Sodium ethanoate
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Other names
Hot ice (Sodium acetate trihydrate)
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Identifiers | |
CAS Number
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127‑09‑3 N 6131‑90‑4 (trihydrate) N |
ChEBI | CHEBI:32954 Y |
ChEMBL | ChEMBL1354 Y |
ChemSpider | 29105 Y |
EC Number | 204-823-8 |
Jmol interactive 3D | Image |
PubChem | 517045 |
RTECS number | AJ4300010 (anhydrous) AJ4580000 |
UNII | NVG71ZZ7P0 Y |
InChI
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SMILES
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Properties | |
Chemical formula
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C2H3NaO2 |
Molar mass | 82.03 g·mol−1 |
Appearance | White deliquescent powder |
Odor | Vinegar |
Density | 1.528 g/cm3 (20 °C, anhydrous) 1.45 g/cm3 (20 °C, trihydrate)[1] |
Melting point | 324 °C (615 °F; 597 K) (anhydrous) |
Boiling point | 881.4 °C (1,618.5 °F; 1,154.5 K) (anhydrous) |
Solubility in water
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Anhydrous: 119 g/100 mL (0 °C) |
Solubility | Soluble in alcohol, hydrazine, SO2[3] |
Solubility in methanol | 16 g/100 g (15 °C) 16.55 g/100 g (67.7 °C)[3] |
Solubility in ethanol | Trihydrate: 5.3 g/100 mL |
Solubility in acetone | 0.5 g/kg (15 °C)[3] |
Acidity (pKa) | 24 (20 °C)[3] 4.76 CH3COOH[4] |
Basicity (pKb) | 9.25 |
Refractive index (nD)
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1.464 |
Structure | |
Crystal structure
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Monoclinic |
Thermochemistry | |
Specific
heat capacity (C) |
100.83 J/mol·K (anhydrous)[5] 229 J/mol·K (trihydrate)[6] |
Std molar
entropy (S |
138.1 J/mol·K (anhydrous)[5] 262 J/mol·K (trihydrate)[1] |
Std enthalpy of
formation (ΔfH |
-709.32 kJ/mol (anhydrous)[3] -1604 kJ/mol (trihydrate)[1] |
Gibbs free energy (ΔfG˚)
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-607.7 kJ/mol (anhydrous)[3] |
Pharmacology | |
ATC code | B05XA08 |
Hazards | |
Main hazards | Irritant |
Safety data sheet | External MSDS |
NFPA 704 |
1
1
0
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Flash point | >250 °C (482 °F; 523 K) [4] |
Autoignition
temperature |
600 °C (1,112 °F; 873 K)[4] |
Lethal dose or concentration (LD, LC): | |
LD50 (Median dose)
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3530 mg/kg (oral, rat) |
Related compounds | |
Other anions
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Sodium formate Sodium propionate |
Other cations
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Potassium acetate Calcium acetate |
Related compounds
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Sodium diacetate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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N verify (what is YN ?) | |
Infobox references | |
Sodium acetate, CH3COONa, also abbreviated NaOAc,[7] also known as sodium ethanoate, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses.
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. In processing cotton for disposable cotton pads, sodium acetate is used to eliminate the buildup of static electricity.
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.[8]
Sodium acetate may be added to food as a seasoning, sometimes in the form of sodium diacetate, a one-to-one complex of sodium acetate and acetic acid,[9] given the E-number E262. It is often used to give potato chips a salt and vinegar flavor.
As the conjugate base of acetic acid, a solution of sodium acetate 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).
Sodium acetate is also used in heating pads, hand warmers, and hot ice. Sodium acetate trihydrate crystals melt at 136.4 °F/58 °C[10] (to 137.12 °F/58.4 °C),[11] dissolving in their water of crystallization. When they are 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 bond-forming process of crystallization is exothermic.[12][13] The latent heat of fusion is about 264–289 kJ/kg.[10] 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.[14]
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 variable concentration acetic acid, commonly known in its 5–8% solution as vinegar, with sodium carbonate ("washing soda"), sodium bicarbonate ("baking soda"), or sodium hydroxide ("lye"). 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 is displaced from sodium bicarbonate or carbonate, as is the monatomic hydrogen from the hydroxide in acetic acid, forming the intermediate 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.
Industrially, sodium acetate is prepared from glacial acetic acid and sodium hydroxide.
Sodium acetate can be used to form an ester with an alkyl halide such as bromoethane:
Caesium salts catalyze this reaction.
Wikimedia Commons has media related to Sodium acetate. |
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AcOH | He | ||||||||||||||||||
LiOAc | Be(OAc)2 BeAcOH |
B(OAc)3 | ROAc | NH4OAc | AcOAc | FAc | Ne | ||||||||||||
NaOAc | Mg(OAc)2 | Al(OAc)3 ALSOL |
Si | P | S | ClAc | Ar | ||||||||||||
KOAc | Ca(OAc)2 | Sc(OAc)3 | Ti(OAc)4 | VO(OAc)3 | Cr(OAc)2 | Mn(OAc)2 MnAc3 |
Fe(OAc)2 FeAc3 |
Co(OAc)2, CoAc3 |
Ni(OAc)2 | Cu(OAc)2 | Zn(OAc)2 | Ga(OAc)3 | Ge | As | Se | BrAc | Kr | ||
RbOAc | Sr(OAc)2 | Y(OAc)3 | Zr(OAc)4 | Nb | Mo(OAc)2 | Tc | Ru | Rh | Pd(OAc)2 | AgOAc | Cd(OAc)2 | In | Sn(OAc)2 SnAc4 |
Sb(OAc)3 | Te | IAc | Xe | ||
CsOAc | Ba(OAc)2 | Hf | Ta | W | Re | Os | Ir | Pt(OAc)2 | Au | Hg2(OAc)2, HgAc2 |
TlOAc Tl(OAc)3 |
Pb(OAc)2 Pb(OAc)4 |
Bi(OAc)3 | Po | At | Rn | |||
Fr | Ra | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Uut | Fl | Uup | Lv | Uus | Uuo | |||
↓ | |||||||||||||||||||
La(OAc)3 | Ce(OAc)x | Pr | Nd | Pm | Sm(OAc)3 | Eu(OAc)3 | Gd(OAc)3 | Tb | Dy(OAc)3 | Ho(OAc)3 | Er | Tm | Yb(OAc)3 | Lu(OAc)3 | |||||
Ac | Th | Pa | UO2(OAc)2 | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
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リンク元 | 「酢酸ナトリウム」 |
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