Sodium oxalate

Last updated
Sodium oxalate
Preferred IUPAC name
Disodium oxalate
Other names
Oxalic acid, disodium salt
Sodium ethanedioate
  • 62-76-0 Yes check.svgY [1]
3D model (JSmol)
ECHA InfoCard 100.000.501 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-550-3
PubChem CID
RTECS number
  • K11750000
  • InChI=1S/C2H2O4.2Na/c3-1(4)2(5)6;;/h(H,3,4)(H,5,6);;/q;2*+1/p-2 X mark.svgN
  • C(=O)(C(=O)[O-])[O-].[Na+].[Na+]
Molar mass 133.999 g mol−1
Density 2.34 g cm−3
Melting point 260 °C (500 °F; 533 K)decomposes above 290 °C [2]
2.69 g/100 mL (0 °C)
3.7 g/100 mL (20 °C)
6.25 g/100 mL (100 °C)
Solubility soluble in formic acid
insoluble in alcohol, ether
-1318 kJ/mol
Hazards [3]
Safety data sheet Oxford MSDS [ unreliable source ]
GHS pictograms GHS-pictogram-exclam.svg
GHS Signal word Warning
H302, H312
P280, P301+P312, P302+P352
NFPA 704 (fire diamond)
Lethal dose or concentration (LD, LC):
11160 mg/kg (oral, rat) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium oxalate, or disodium oxalate, is the sodium salt of oxalic acid with the formula Na2C2O4. It is a white, crystalline, odorless solid, that decomposes above 290 °C. [2]


Disodium oxalate can act as a reducing agent, and it may be used as a primary standard for standardizing potassium permanganate (KMnO4) solutions.

The mineral form of sodium oxalate is natroxalate. It is only very rarely found and restricted to extremely sodic conditions of ultra-alkaline pegmatites. [4]


Sodium oxalate can be prepared through the neutralization of oxalic acid with sodium hydroxide (NaOH) in a 1:2 acid-to-base molar ratio. Evaporation yields the anhydrous oxalate [5] that can be thoroughly dried by heating to between 200 and 250 °C. [2]

Half-neutralization can be accomplished with NaOH in a 1:1 ratio which produces NaHC2O4, monobasic sodium oxalate or sodium hydrogenoxalate.

Alternatively, it can be produced by decomposing sodium formate by heating it at a temperature exceeding 360 °C.[ citation needed ]


Sodium oxalate starts to decompose above 290 °C into sodium carbonate and carbon monoxide: [2]

+ CO

When heated at between 200 and 525°C with vanadium pentoxide in a 1:2 molar ratio, the above reaction is suppressed, yielding instead a sodium vanadium oxibronze with release of carbon dioxide [6]

+ 2 V
→ 2 Na
+ 2xCO

with x increasing up to 1 as the temperature increases.

Sodium oxalate is used to standardize potassium permanganate solutions. It is desirable that the temperature of the titration mixture be greater than 60 °C to ensure that all the permanganate added reacts quickly. The kinetics of the reaction are complex, and the manganese(II) ions formed catalyze the further reaction between permanganate and oxalic acid (formed in situ by the addition of excess sulfuric acid). The final equation is as follows: [7]

5 Na2C2O4 + 2 KMnO4 + 8 H2SO4 → K2SO4 + 5 Na2SO4 + 2 MnSO4 + 10 CO2 + 8 H2O

Biological activity

Like several other oxalates, sodium oxalate is toxic to humans. It can cause burning pain in the mouth, throat and stomach, bloody vomiting, headache, muscle cramps, cramps and convulsions, drop in blood pressure, heart failure, shock, coma, and possible death. Mean lethal dose by ingestion of oxalates is 10-15 grams/kilogram of body weight (per MSDS).

Sodium oxalate, like citrates, can also be used to remove calcium ions (Ca2+) from blood plasma. It also prevents blood from clotting. Note that by removing calcium ions from the blood, sodium oxalate can impair brain function, and deposit calcium oxalate in the kidneys.

Related Research Articles

Carbonate Salts of carbonate

A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula of CO2−
. The name may also refer to a carbonate ester, an organic compound containing the carbonate group C(=O)(O–)2.

In chemistry, a salt is a chemical compound consisting of an ionic assembly of a positively charged cation and a negatively charged anion, which results in a compound with no net electric charge. A common example is table salt, a molecule of which has a positively charged sodium ion and a negatively charged chloride ion.

Potassium ferrocyanide Chemical compound

Potassium ferrocyanide is the inorganic compound with formula K4[Fe(CN)6]·3H2O. It is the potassium salt of the coordination complex [Fe(CN)6]4−. This salt forms lemon-yellow monoclinic crystals.

Oxidizing agent Chemical compound used to oxidize another substance in a chemical reaction

An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize other substances — in other words to accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens.

Manganese dioxide Chemical compound

Manganese dioxide is the inorganic compound with the formula MnO
. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery. MnO
is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
is α polymorph that can incorporate a variety of atoms in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
as a possible cathode for lithium-ion batteries.

Potassium permanganate Chemical compound

Potassium permanganate is an inorganic compound with the chemical formula KMnO4 and composed of K+ and MnO
. It is a purplish-black crystalline salt, that dissolves in water to give intensely pink or purple solutions.

Oxalic acid Simplest dicarboxylic acid

Oxalic acid is an organic acid with the IUPAC name ethanedioic acid and formula HO2C−CO2H. It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early investigators isolated oxalic acid from flowering plants of the genus Oxalis, commonly known as wood-sorrels. It occurs naturally in many foods, but excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.

Gravimetric analysis

Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to determine the same analyte's mass in a mixture, as long as the relative quantities of the other constituents are known.

Oxalate Any derivative of oxalic acid; chemical compound containing oxalate moiety

Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42-. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl oxalate (C2O4(CH3)2). It is a conjugate base of oxalic acid. At neutral pH in aqueous solution, oxalic acid converts completely to oxalate.

Permanganate Chemical compound

A permanganate is the general name for a chemical compound containing the manganate(VII) ion, MnO
, the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion has tetrahedral geometry. Permanganate solutions are purple in color and are stable in neutral or slightly alkaline media. The exact chemical reaction is dependent upon the organic contaminants present and the oxidant utilized. For example, trichloroethane (C2H3Cl3) is oxidized by permanganate ions to form carbon dioxide (CO2), manganese dioxide (MnO2), hydrogen ions (H+), and chloride ions (Cl).

Vanadium(V) oxide Chemical compound

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula V2O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

Permanganic acid (or manganic(VII) acid) is the inorganic compound with the formula HMnO4. This strong oxoacid has been isolated as its dihydrate. It is the conjugate acid of permanganate salts. It is the subject of few publications and its characterization as well as its uses are very limited.

Potassium manganate Chemical compound

Potassium manganate is the inorganic compound with the formula K2MnO4. This green-colored salt is an intermediate in the industrial synthesis of potassium permanganate (KMnO4), a common chemical. Occasionally, potassium manganate and potassium permanganate are confused, but they are different compounds with distinctly different properties.

Sodium formate Chemical compound

Sodium formate, HCOONa, is the sodium salt of formic acid, HCOOH. It usually appears as a white deliquescent powder.

Sodium permanganate Chemical compound

Sodium permanganate is the inorganic compound with the formula NaMnO4. It is closely related to the more commonly encountered potassium permanganate, but it is generally less desirable, because it is more expensive to produce. It is mainly available as the monohydrate. This salt absorbs water from the atmosphere and has a low melting point. Being about 15 times more soluble than KMnO4, sodium permanganate finds some applications where very high concentrations of MnO4 are sought.

Permanganometry is one of the techniques used in chemical quantitative analysis. It is a redox titration that involves the use of permanganates to measure the amount of analyte present in unknown chemical samples. It involves two steps, namely the titration of the analyte with potassium permanganate solution and then the standardization of potassium permanganate solution with standard sodium oxalate solution. The titration involves volumetric manipulations to prepare the analyte solutions.

Sodium ferrioxalate Chemical compound

Sodium ferrioxalate is a chemical compound with the formula Na3Fe(C2O4)3. It is also called sodium oxalatoferrate or sodium trisoxalatoferrate.

Magnesium oxalate Magnesium compound

Magnesium oxalate is an organic compound comprising a magnesium cation with a 2+ charge bonded to an oxalate anion. It has the chemical formula MgC2O4. Magnesium oxalate is a white solid that comes in two forms: an anhydrous form and a dihydrate form where two water molecules are complexed with the structure. Both forms are practically insoluble in water and are insoluble in organic solutions.

Sodium hydrogenoxalate Partly deprotonated oxalic acid

Sodium hydrogenoxalate is salt of formula NaHC
, consisting of sodium cations Na+
and hydrogenoxalate anions HC
or -. The anion can be described as the result of removing one hydrogen ion H+
from oxalic acid H
, or adding one to the oxalate cation C


  1. 1 2 "ChemIDplus - 62-76-0 - ZNCPFRVNHGOPAG-UHFFFAOYSA-L - Disodium oxalate - Similar structures search, synonyms, formulas, resource links, and other chemical information". NIH. Retrieved 7 January 2019.
  2. 1 2 3 4 Yoshimori T1, Asano Y, Toriumi Y, Shiota T. (1978) "Investigation on the drying and decomposition of sodium oxalate". Talanta, volume 25, issue 10, pages 603-605. doi : 10.1016/0039-9140(78)80158-1
  3. GHS: GESTIS 570199
  4. "Natroxolate" (PDF). RRUFF. Mineral Data Publishing. Retrieved 7 January 2019.
  5. H. W. Foote and John E. Vance (1933), "The system; sodium iodate, sodium oxalate, water". American Journal of Science, series 5, volume 26, issue 151, pages 16-18. doi : 10.2475/ajs.s5-26.151.16
  6. D. Ballivet-Tkatchenko, J. Galy, -M. Savariault (1994): "Thermal decomposition of sodium oxalate in the presence of V2O5: Mechanistic approach of sodium oxibronzes formation". Thermochimica Acta , volume 232, issue 2, pages 215-223. doi : 10.1016/0040-6031(94)80061-8
  7. Mcbride, R. S. (1912). "The standardization of potassium permanganate solution by sodium oxalate". J. Am. Chem. Soc. 34 (4): 393–416. doi:10.1021/ja02205a009.