This article deals with Sodium potassium tartrate, also known as Rochelle salt, which is a double salt of tartaric acid. It was first prepared in the year 1672 by an apothecary, Pierre Seignette, of La Rochelle, France. Rochelle salt is a white crystalline powder and a slightly bitter taste. It has a pH range of 6.5 – 8.5. It is obtained by the reaction of Sodium Hydroxide on the crude Cream of Tartar which is a by-product of the Wine Industry. It is almost insoluble in alcohol and ether.
Properties of Sodium Potassium Tartrate
Sodium Potassium Tartrate Uses
Used in Laboratory reagent, one of the ingredients in Biuret reagent to measure the concentration of protein.
It is used in the electroplating process (Increases cathode efficiency.), in electronics, and piezoelectricity.
It is used in cigarette paper. (Delays the consumption of cigarette paper.)
It helps in maintaining alkaline pH.
It is used in the silvering of mirrors. (Act as a reducing agent)
It is also used in the Pharmaceutical Industry.
It is used in gas purification.
It is an ingredient in Fehling's solution test (reagent used in reducing sugars) and determination of uric acid.
Sodium Potassium Tartrate Structure
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Sodium Potassium tartrate/ Rochelle salt contains ten oxygen atoms, twelve hydrogen atoms, four carbon atoms, one potassium atom, and one sodium atom.
Reactions Involved in the Preparation of Rochelle Salt/Potassium Tartrate
The first step involves the Conversion of sodium bicarbonate to sodium carbonate
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Potassium bitartrate reacts with sodium carbonate to generate Sodium Potassium Tartrate / Rochelle salt:
KHC₄H₄O₆ + Na₂CO₃ → C₄H₄O₆KNa . 4H₂O
Did you know?
Rochelle Salt must be stored in a dry place with airtight packing and, away from humidity and in normal temperature conditions and its IUPAC name is sodium potassium-2,3-dihydroxy butane-1,4-dioate.