Substance profile
Oxalic acid
Oxalic acid is an anhydrous oxalic acid, crystallized from glacial acetic acid is orthorhombic and is odorless.
01 · Identification
What Oxalic acid is
Oxalic acid is an anhydrous oxalic acid, crystallized from glacial acetic acid is orthorhombic and is odorless. Its molecular formula is C2H2O4 and its molecular weight is 90.03 g/mol. It melts at 190 °C.
Under the GHS it carries the signal word Warning. It is classed as corrosives.
Other names for Oxalic acid
- C2H2O4
- Aktisal
- Aquisal
- Ethanedioic Acid
- Ethanedionic Acid
- Oxalic Acid (Aqueous)
- Oxalic Acid (As Dihydrate)
- Oxalic Acid Dihydrate
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H312 | Harmful in contact with skin. |
| H302 | Harmful if swallowed. |
Precautionary statements: P270, P280, P301, P302, P312, P330, P352
03 · Physical and chemical properties
Oxalic acid properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | Sublimes | sublimes | NIOSH |
| Sublimes (NIOSH, 2024) | sublimes | CAMEO | |
| sublimes | sublimes | OSHA | |
| Melting point | 189.5 °C (373.1 °F) | ICSC | |
| 188.89 °C (372 °F) | OSHA | ||
| 189.5 °C (373.1 °F) | decomposes, DECOMPOSES | HSDB | |
| Density | 1.9 g/cm³ | HSDB | |
| Solubility | VERY SOL IN ETHANOL; SLIGHTLY SOL IN ETHER; INSOL IN BENZENE, CHLOROFORM, PETROLEUM ETHER | HSDB | |
| 14% | NIOSH | ||
| Water solubility of 220,000 mg/l at 25 °C | at 25 °C | HSDB | |
| Vapor pressure | 0.001 mmHg | at 20 °C | CAMEO |
| 0.001 mmHg | below this value | NIOSH | |
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO | |
| Lower explosive limit (LEL) | Combustible Solid | NIOSH | |
| Vapor density | 4.3 (air = 1) | CAMEO |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Handling and storage
Storing and handling Oxalic acid
Storage conditions
STORE IN COOL, DRY, WELL-VENTILATED LOCATION. /OXALIC ACID DIHYDRATE/
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Reacts with strong alkalies, strong oxidizing materials, chlorites, and hypochlorites. /Oxalic acid dihydrate/
Source: Hazardous Substances Data Bank (HSDB)
Reactivity
OXALIC ACID is hygroscopic and sensitive to heat. This compound may react violently with furfuryl alcohol, silver, sodium, perchlorate, sodium hypochlorite, strong oxidizers, sodium chlorite, acid chlorides, metals and alkali metals. (NTP, 1992). The heating of mixtures of Oxalic acid and urea has lead to explosions. This is due to the rapid generation of the gases CO2, CO, and NH3 [Praxis Naturwiss. Chem., 1987, 36(8), 41-42]. Oxalic acid and urea react at high temperatures to form toxic and flammable ammonia and carbon monoxide gases, and inert CO2 gas [Von Bentzinger, R. et al., Praxis Naturwiss. Chem., 1987, 36(8), 41-42].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Oxalic acid in the storage compatibility matrix →
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