Sodium hydrogenoxalate
Partly deprotonated oxalic acid
Sodium hydrogenoxalate or sodium hydrogen oxalate is a chemical compound with the chemical formula NaHC2O4. It is an ionic compound. It is a sodium salt of oxalic acid H2C2O4. It is an acidic salt, because it consists of sodium cations Na+ and hydrogen oxalate anions HC2O−4 or HO−C(=O)−CO−2, in which only one acidic hydrogen atom in oxalic acid is replaced by sodium atom. The hydrogen oxalate anion can be described as the result of removing one hydrogen ion H+ from oxalic acid, or adding one to the oxalate anion C2O2−4.
Properties
Hydrates
The compound is commonly encountered as the anhydrous form or as the monohydrate NaHC2O4·H2O. Both are colorless crystalline solids at ambient temperature.
The monohydrate can be obtained by evaporating a solution of the compound at room temperature.
Reactions
Upon being heated, sodium hydrogenoxalate converts to oxalic acid and sodium oxalate, the latter of which decomposes into sodium carbonate and carbon monoxide.
2 NaHC2O4 → Na2C2O4 + H2C2O4
Na2C2O4 → Na2CO3 + CO
Toxicity
The health hazards posed by this compound are largely due to its acidity and to the toxic effects of oxalic acid and other oxalate or hydrogenoxalate salts, which can follow ingestion or absorption through the skin. The toxic effects include necrosis of tissues due to sequestration of calcium ions Ca2+, and the formation of poorly soluble calcium oxalate crystals in the kidneys that can obstruct the kidney tubules.
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