What Is Sodium Oxalate?
Sodium oxalate is an inorganic compound with the chemical formula Na2C2O4. It has a molecular weight of 134.0 g/mol, a density of 2.34 g/cm3, a melting point between 250℃ and 270℃, and a CAS number of 62-76-0. At room temperature and pressure, sodium oxalate appears as a colorless or white, odorless crystalline powder. It is primarily used as a reagent in titration experiments.
Under the Poisonous and Deleterious Substances Control Law, Sodium Oxalate is classified as a harmful substance.
Uses of Sodium Oxalate
Sodium oxalate is widely utilized as a standard reagent due to its high purity and stability, especially in redox titration experiments for determining hydrogen peroxide levels with potassium permanganate (KMnO4) as the oxidizing agent. In these reactions, sodium oxalate acts as a reducing agent, resulting in carbon dioxide and water. The titration endpoint is indicated by a clear change in color due to the reaction dynamics.
To ensure accurate endpoint determination, the reaction mixture should be heated to about 60°C and stirred thoroughly, facilitating a faster reaction rate.
Other applications include its use as a dyeing aid, bleaching aid, plating bath additive, in leather tanning, as a reducing agent, and as a raw material in catalyst preparation and metal complex research.
Properties of Sodium Oxalate
Sodium oxalate, an ionic solid, is slightly soluble in water but insoluble in ethanol and other organic solvents. It is a salt formed from the reaction of oxalic acid, a weak acid, with sodium hydroxide, a strong base, making its aqueous solutions weakly basic.
Other Information on Sodium Oxalate
1. Manufacturing Process of Sodium Oxalate
Sodium oxalate can be synthesized by reacting oxalic acid with sodium hydroxide. Interestingly, plants produce oxalic acid during photosynthesis, but due to its toxicity, it is often found combined with sodium and calcium ions in various forms across different plant species. Spinach, for example, is notably high in sodium oxalate content.
2. Hazards of Sodium Oxalate
Sodium oxalate decomposes to produce carbon dioxide when heated, potentially reducing oxygen levels in enclosed spaces and causing symptoms like dizziness and nausea. Therefore, adequate ventilation is crucial when handling large quantities. Oxalic acid, a hydrolysis product, is irritating to skin and eyes, necessitating the use of protective gear such as eyewear, rubber gloves, and lab coats during handling. In case of skin contact, immediate rinsing with water is advised.