Potassium sodium tartrate
From Wikipedia, the free encyclopedia
| Potassium sodium tartrate | |
|---|---|
-tartrate.png/200px-K-Na-L-(+)-tartrate.png) |
|
| IUPAC name | Potassium sodium tartrate |
| Other names | E337 |
| Identifiers | |
| CAS number | [304-59-6] |
| EINECS number | |
| Properties | |
| Molecular formula | KNaC4H4O6·4H2O |
| Molar mass | 282.1 g/mol |
| Melting point |
75 °C |
| Boiling point |
220 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Potassium sodium tartrate is a double salt first prepared (in about 1675) by an apothecary, Pierre Seignette, of La Rochelle, France. As a result the salt was known as Seignette's salt or Rochelle salt.
It is a colorless to blue-white salt crystallizing in the orthorhombic system. Its molecular formula is KNaC4H4O6·4H2O. It is slightly soluble in alcohol but more completely soluble in water. It has a specific gravity of about 1.79, a melting point of approximately 75 °C, and has a saline, cooling taste. As a food additive, its E number is E337.
It has been used medicinally as a purgative but in more recent years its piezoelectric properties have been more important and it has found usage in phonograph pickups and other sensing devices. It has also been used in the process of silvering mirrors. It is an ingredient of Fehling's solution, formerly used in the determination of reducing sugars in solutions.
In organic synthesis, it is used in aqueous workups to break up emulsions, particularly for reactions in which an aluminum-based hydride reagent was used.
It is also an ingredient in the Biuret reagent which is used to measure protein concentration.
[edit] Preparation
Rochelle salt (potassium sodium tartrate, NaKC4H4O6) can easily be prepared from potassium bitartrate (KHC4H4O6) and sodium carbonate (Na2CO3). First heat a potassium bitartrate solution. Add sodium carbonate to the still hot solution. Add sodium carbonate until no more reacts (Effervescence will occur). Filter the solution while hot and then heat to evaporate the water. After continued heating potassium sodium tartrate will precipitate.
[edit] References
 |
This article does not cite any references or sources. (October 2007) Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. |
