Sodium potassium tartrate, often recognized by its more familiar name Rochelle salt, stands as a pivotal inorganic compound with the chemical formula KNaC4H4O6·4H2O. This substance appears as colorless to white crystalline material, widely utilized in laboratories, chemical analysis, and industrial settings. In daily work, this compound manages to bring together versatility and reliability as a key ingredient in many chemical protocols, including Fehling's and Seidlitz powders.
Chemically, sodium potassium tartrate consists of sodium (Na), potassium (K), carbon (C), hydrogen (H), and oxygen (O) in a tartrate framework stabilized with four molecules of water. The well-ordered crystalline structure gives it a monoclinic form. Its molecular weight checks in at 282.2 g/mol, and a deeper look at its lattice reveals strong hydrogen bonds due to the water of crystallization. As someone who has spent hours sifting through chemical handbooks, it quickly becomes clear this four-water hydrate format is crucial for its physical stability and reactivity.
At room temperature, sodium potassium tartrate most often appears as transparent, glassy crystals or a crystalline powder. Some suppliers offer the material in other physical forms: dense solid lumps, thin flakes, or the more granular pearls suitable for precise dosing. The compound carries a specific gravity around 1.79 and maintains a density close to 1.8 g/cm3. Solubility in water is pronounced; just about 200 grams of sodium potassium tartrate dissolve in one liter at 20°C, an attribute that makes it popular for preparing analytical solutions. No significant solubility presents in ethanol or organic solvents. Whenever someone handles bulk powder or finer crystals, a distinct saline taste comes from its tartrate backbone.
Industries and laboratories typically demand a high purity reagent, with sodium potassium tartrate offered in grades exceeding 99% purity, free from detrimental impurities like heavy metals or oxidizing residues. Checking certificates of analysis from major suppliers usually confirms tight controls on arsenic, lead, and sulfate levels, so users can depend on reproducible results throughout research or production. Flake and pearl forms often rate slightly higher for solution preparation, while ultra-fine powder versions favor titration experiments for swift dissolution.
Globally, sodium potassium tartrate is traded under the Harmonized System (HS) Code 29181300, grouped under salts and esters of tartaric acid. Customs authorities identify it through this code, ensuring proper regulation and tracking across borders. Shipments labeled with this code allow international companies and research facilities to maintain compliance, critical for legal import and export, and make inventory control easier. Labeling meets international chemical transport standards, with robust documentation and handling guidance.
Sodium potassium tartrate does not register as acutely toxic or flammable, yet users still treat it with respect in work environments. Chronic ingestion or substantial skin contact can prove harmful—prolonged exposure may lead to gastrointestinal upset. Eyes, mucous membranes, and open wounds deserve additional protection. Every package should come with a clear GHS-compliant safety label and safety data sheet outlining the minimal but real risk it presents. Good ventilation, dust control, and the use of gloves and goggles keep risk low. Clean-up after spills involves nothing more advanced than sweeping or vacuuming under dry conditions, followed by water rinse for residual particles.
Rochelle salt excels in its role as a raw chemical in precision analysis, especially in Fehling’s solution for reducing sugar determinations. It also stabilizes solutions in silvering mirrors, aids buffer solutions, and acts as a sequestering agent in water softening. Some manufacturers have historically leaned on it for piezoelectric applications, owing to its ability to create voltage when compressed. Curious minds in academic labs discover its value quick—hands-on titrations and colorimetric tests would lose accuracy without this reliable salt, and anyone responsible for calibration values the certainty of consistent, reagent-grade batches.
Providing high-quality chemical products and logistics solutions for global trade partners.
