Potassium sodium tartrate

  • Potassium sodium tartrate tetrahydrate
  • Sodium potassium tartrate
  • Tartaric acid potassium sodium salt
  • E 337

Colorless solid

Fixed

1.79 g · cm -3

70-80 ° C ( tetrahydrate)

Decomposition at 220 ° C

  • Good in water ( 630 g · l-1 at 20 ° C)
  • Poorly in ethanol

Template: Infobox chemical / molecular formula search available

Rochelle salt is a salt of tartaric acid. The French pharmacist, after which it was named, Pierre Seignette, discovered it in 1672. It is a double salt containing potassium and sodium ions, with today's correct name Potassium sodium tartrate tetrahydrate ( KNaC4H4O6 · 4 H2O). The tartrates are the salts of tartaric acid, Rochelle salt is derived from the two bases of potash and soda from.

The Rochelle salt was discovered in La Rochelle and is therefore also called Rochellais salt. Obsolete names are tartrate Natronkalium or Natronweinstein. The result of the application in the pharmaceutical industry ( mild emetic ) important Latin names are Tartarus natronatus, Natrokali tartaricum, potassium tartaricum natronatum (French Tartrate de soude et de potasse, Sel de Seignette, Eng. Tartarated soda, Salt of Seignette ).

At Rochelle salt ferroelectricity was discovered.

Production

Potassium sodium tartrate can be made from cream of tartar and soda, by treating a solution of soda with cream of tartar until there is no escape of carbonic acid takes place more. After evaporation of the filtered liquor in the Turkish form beautiful crystals are dried at very low heat, otherwise they lose their transparency or transparency.

Properties and Uses

The crystals form large, water-white, rhombic columns. The salt melts when heated in its crystal water, but is otherwise fairly stable in air. It dissolves in very little water, has a mild salty taste and is used as a cooling, slightly laxative agents, eg as Seidlitzpulver. In analytical chemistry it is used as a tool for the detection of reducing sugars with Fehling's solution II or Nylanders reagent. This makes use of that it is a good chelator ( complexing ) and complexed copper and bismuth ions and thereby binds.

In use as a chelating agent, in place of the salt of a different Seignette tartrate can be used which is an uncharged molecule with appropriate atoms, as long as this is not even as a ligand for the complex bond with the Seignettsalz in question. That the venal Rochelle salt composed of potassium sodium tartrate, is related to the cost of this product. Potassium hydrogen tartrate is very common in nature and can be obtained in a simple manner. Also required for the dosage and the neutralization of an alkali metal carbonate is relatively cheap when sodium carbonate is used.

Because of its piezoelectric properties was used to make the Kristalltonabnehmers.

It is in the EU as a food additive under the E number 337 approved ( usually use as an acidity regulator ).

Swell

  • Carboxylic acid salt
  • Potassium compound
  • Sodium compound
  • Electric Technical Material
  • Acidulants
CAS registry number Potassium bitartrate
296183
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