| Sodium Acetate |
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Sodium acetate, also known as '''sodium ethanoate''', is used in a number of industries:
The last usage is seen in consumer Heating Pad s. When these pads are solid, they are composed of sodium acetate trihydrate, or hydrated crystals of sodium acetate. If the solid is heated to the boiling point of water, the water molecules will be released from the crystals. This freed water can then dissolve the sodium acetate. After cooling, the sodium acetate remains dissolved even though the solution is Supersaturated . This means that the energy that was required to release the water molecules from the crystals and dissolve the sodium acetate into that water still remains in the system even though the temperature has dropped. The clicking of a disk within the pad triggers the Crystallization of the sodium acetate trihydrate. When the crystals form, the energy that was required to initially dissolve them is then released. This release of energy raises the temperature to 54° C . For the above reasons, this is technically not a demonstration of the heat that is released during a phase change. It is an exothermic chemical reaction. The process is theoretically repeatable indefinitely, although the containing pouch will eventually break in practice. [http://www.atmos.washington.edu/2003Q3/101/demonstrations/fake_latentheat_supersaturation.html REACTIONS Sodium acetate can be used as a reagent to form an Ester using an alkyl halide such as Bromoethane . H3C-COO- Na+ + Br-CH2-CH3 → H3C-COO-CH2-CH3 + NaBr SYNTHESIS OF SODIUM ACETATE Sodium acetate can be obtained easily by the reaction of Acetic Acid with Sodium Bicarbonate . H3C-COOH + Na+ {Link without Title} - → H3C-COO- Na+ + H2CO3 The resulting Carbonic Acid decomposes quickly to Carbon Dioxide and Water so the equilibrium is pushed to the right. This is the well-known "fizzing" reaction between baking soda and Vinegar . By subsequently boiling off most of the water, one can refine either a concentrated solution of sodium acetate or actual crystals. However (like most reactions) the baking soda and vinegar must be combined in exact proportions to avoid excess acid or bicarbonate in the final product. SEE ALSO |
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