Sodium oxalate is a salt derived from oxalic acid, known chemically as disodium oxalate. It typically appears as a white, crystalline, and odorless solid. This inorganic compound is industrially significant, finding utility in both laboratory settings and larger-scale industrial processes. Its chemical structure makes it an important reagent in analytical chemistry and a precursor in material production.
The Formula and Molecular Structure
The chemical formula for sodium oxalate is \(\text{Na}_2\text{C}_2\text{O}_4\). This indicates the composition: two sodium atoms, two carbon atoms, and four oxygen atoms. It is an ionic compound formed by the interaction of two positively charged sodium ions (\(\text{Na}^+\)) bonded to one negatively charged oxalate anion (\(\text{C}_2\text{O}_4^{2-}\)). Covalent bonds hold the carbon and oxygen atoms together within the oxalate anion. The overall molar mass of the compound is approximately 134.00 grams per mole.
Key Physical and Chemical Characteristics
Sodium oxalate is a fine, white, crystalline powder with a density of 2.34 grams per cubic centimeter. It is thermally stable, beginning to decompose between \(250^{\circ}\text{C}\) and \(290^{\circ}\text{C}\). It is moderately soluble in water, with solubility increasing significantly at higher temperatures. Conversely, it is insoluble in common organic solvents like alcohol. The compound is used in analytical chemistry as a primary standard for titrations because it can be obtained in a highly pure and stable form.
Practical Applications and Uses
The stability and reducing properties of sodium oxalate lead to several specialized applications. In analytical chemistry, it serves as a standard to determine the concentration of oxidizing agents, such as potassium permanganate solutions, through titration experiments. In metallurgy, it is utilized as a precipitating agent for separating and purifying rare earth elements by forming insoluble metal oxalate precursors. It also acts as a mordant in the textile industry to help fix dyes to fabrics. Furthermore, it is a precursor in the synthesis of high-purity metal oxide nanoparticles for advanced material science applications.
Safety Considerations and Toxicity
Sodium oxalate is considered toxic if ingested and must be handled with caution. The primary danger comes from the oxalate ion, which binds strongly to calcium ions in the bloodstream. This binding leads to hypocalcemia, causing symptoms like muscle cramps and a drop in blood pressure. The binding of calcium can result in the formation of insoluble calcium oxalate crystals within the body. These crystals can accumulate in the kidneys, potentially leading to renal damage or failure.
In case of accidental ingestion, first aid often involves administering a calcium-containing solution to help counteract the effects of the oxalate ion. Proper handling in a laboratory or industrial setting requires specific personal protective equipment. Workers should wear protective gloves, clothing, and eye protection to prevent skin and eye contact. Working in a well-ventilated area is also necessary to avoid inhalation of the fine crystalline dust, which can irritate the respiratory tract.