Potassium sodium tartrate

Rochellesalt

Potassium sodium tartrate, also known as Rochelle salt or by its chemical formula KNaC₄H₄O₆, is a double salt of tartaric acid with potassium and sodium ions. It is commonly used in a variety of applications, including the food industry as an emulsifier, in the medical field as a laxative, and in the chemical industry for the preparation of other tartrates and as a component in Fehling's solution, a chemical reagent used to differentiate between water-soluble carbohydrates.

History

Potassium sodium tartrate was first prepared by an apothecary in Rochelle, France, in the 17th century, which is how it got its common name, Rochelle salt. It played a significant role in the development of chemistry in the 18th and 19th centuries, particularly in the work of Carl Wilhelm Scheele and Justus von Liebig who used it in their research.

Chemical Properties

Potassium sodium tartrate is a colorless to white crystalline powder that is soluble in water. Its aqueous solution is neutral or slightly alkaline. The compound is stable under normal conditions but decomposes when heated, producing carbon dioxide and leaving a residue of potassium carbonate and sodium carbonate.

Applications

Food Industry

In the food industry, potassium sodium tartrate is used as a stabilizer, pH control agent, and emulsifier. It is also a key ingredient in baking powder, where it acts as an acidulant to activate baking soda.

Medical Field

As a mild laxative, it has been used in traditional medicine. However, its use in modern medicine is limited due to the availability of more effective and safer alternatives.

Chemical Industry

Potassium sodium tartrate is essential in the chemical industry, especially as a component of Fehling's solution. Fehling's solution is used to test for the presence of reducing sugars, where the tartrate serves as a complexing agent for copper(II) ions, allowing them to remain in solution at an alkaline pH.

Safety

Potassium sodium tartrate is generally regarded as safe when used in food. However, like all chemicals, it should be handled with care, and appropriate safety measures should be taken to avoid ingestion, inhalation, or contact with skin and eyes in its pure form.

Environmental Impact

The environmental impact of potassium sodium tartrate is considered low. It is biodegradable and does not accumulate in the environment. However, as with all chemical substances, it should be disposed of responsibly to minimize any potential harm to the environment.