Potassium sodium tartrate CAS 304-59-6

Potassium sodium tartrate (molecular formula KNaC4H4O6 · 4H2O), also known as sodium potassium tartrate, Roche salt, or Rochelle salt, is a double salt formed by sodium tartrate and potassium tartrate. It is a colorless to blue white orthorhombic crystal, soluble in water, slightly soluble in alcohol, salty and cool in taste, and slightly alkaline in aqueous solution. Specific gravity 1.79, pH value 6.8-8, melting point 70-80 ° C, slightly weathered in hot air. At 60 ° C, some crystal water is lost, at 100 ° C, 3 water molecules are lost, and at 215 ° C, all crystal water is lost and becomes anhydrous salt. Potassium sodium tartrate is divided into two types: D type and DL type. D type is a colorless and transparent crystal, and its solubility in water is 138.3g per 100ml at 30 ° C. It is insoluble in alcohol. It has chelating properties and can form soluble complexes with metal ions such as copper, iron, lead, chromium, and gold in alkaline solutions. DL type is a white fine-grained crystal with a density of 1.783g/cm3. Melting point of 100 ℃. It has weathering properties in hot air, losing some crystal water at 60 ℃ and all crystal water at 215 ℃. The solubility of 100ml in water at 30 ℃ is 117.62g, which is insoluble in alcohol. Has chelating properties. It can be used as a laxative, food additive, piezoelectric element, as well as a chemical reagent for preparing film reagents, biuret reagents, and as a reducing agent in mirror making.