Sodium acetate



Sodium acetate
IUPAC name sodium acetate (IUPAC)

sodium ethanoate (systematic)

Other names Acetic acid, sodium salt
Properties
Molecular formula CH3COONa
Molar mass 82.03 g/mol (anhydrous)

136.08 g/mol (trihydrate)

Appearance White deliquescent powder
Density 1.45 g/cm³, solid
Melting point

Decomposes at 324 °C

Boiling point

Decomposes

Solubility in water 76 g/100 ml (0°C)
Basicity (pKb) 9.25
Structure
Crystal structure monoclinic
Hazards
MSDS External MSDS
Main hazards Irritant
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Sodium acetate, (also rarely, sodium ethanoate) is the acetic acid. It is an inexpensive chemical produced in industrial quantities for a wide range of uses.

Applications

Sodium acetate is used in the synthetic rubber production.

Sodium acetate is the chemical that gives salt and vinegar chips their flavour. It may also be added to foods as a preservative; in this application it is usually written as "sodium diacetate" and labeled E262.

As the conjugate base of a weak acid, a solution of sodium acetate and acetic acid can act as a buffer to keep a relatively constant pH. This is useful especially in biochemical applications where reactions are pH dependent.

Sodium acetate is also used in consumer heating pads or hand warmers and is also used in "hot ice". When sodium acetate trihydrate crystals (melting point 58 °C) are heated to around 100 °C, they melt. When this melt cools, it gives a latent heat of fusion is about 264–289 kJ/kg.[4]

Preparation

Sodium acetate is inexpensive, and is usually purchased from chemical suppliers, instead of being synthesized in the laboratory. It is sometimes produced in a laboratory experiment by the reaction of sodium hydroxide. These reactions produce sodium acetate(aq), water, and carbon dioxide which leaves the reaction vessel as a gas.

CH3–COOH + Na+[HCO3]– → CH3–COO– Na+ + H2O + CO2

This is the well-known "fizzing" reaction between baking soda and vinegar. 84 grams of sodium bicarbonate react with 750 g of 8% vinegar to make 82 g sodium acetate in water. By subsequently boiling off most of the water, one can refine either a concentrated solution of sodium acetate or actual crystals.

Reactions

Sodium acetate can be used to form an bromoethane:

H3C–COO– Na+ + NaBr

Gallery

References

  1. ^ Crystallization of Supersaturated Sodium Acetate. Journal of Chemical Education.
  2. ^ "Fake" latent heat and supersaturation
  3. ^ How do sodium acetate heat pads work?. HowStuffWorks. Retrieved on 2007-09-03.
  4. ^ Thermal Energy Storage: Systems and Applications, By Ibrahim Dincer, Marc A. Rosen, p. 155 [1]
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium_acetate". A list of authors is available in Wikipedia.