Oxalic Acid properties
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Oxalic Acid Safety Information For Beekeepers

It is highly recommended you consult Safety Data Sheets for oxalic acid dihydrate online

This Oxalic Acid Safety Information for beekeepers, has been gathered from various sources, there are variations in some of the data on the various linked pages of this website, these variations are not thought to be errors, but merely a manifestation of slightly different properties and possibly different measurement methods from different suppliers of the material. As with all information on the web, if the parameter is important to you, check it on several other resources. In particular the figure given for vapour pressure has been seen quoted at a value ten times higher than the figure on this page and one site gives an even higher figure, but at an elevated temperature ( 0.92 mm Hg @ 60°C).

General Information

Synonyms... Ethanedioic acid, ethandionic acid.
Molecular formula... C2H2O4 2H2O
Alternative expression... HOOCCOOH.2H2O
CAS No... 6153-56-6

Physical Data

Appearance... white/transparent crystals
Specific Gravity... 1.65
Melting point... 101.4 - 101.6°C
Boiling Point... 149 - 160°C (sublimes).
Vapour Density... 4.4 (air=1).
Vapour pressure... < 0.001 mm Hg at 20°C
Solubility... 1gm/7ml (water).
Molecular Weight... 126.07.


Stable... Incompatible with bases, acid chlorides, steel, silver, silver compounds, moisture. Avoid contact with metals.


Harmful... If swallowed, inhaled or absorbed through skin.
Corrosive... causes burns. Very destructive of mucous membranes. Typical STEL 2 mg/m3.

Toxicity Data

ORL-WMN LDLO 600 mg kg-1
ORL-RAT LD50 7500 mg kg-1
UNR-RAT LD50 1400 mg kg-1

Risk Phrases

Harmful by inhalation.
Harmful in contact with skin.
Harmful if swallowed.
Causes burns.

Transport Hazard Information

Hazard 8, Corrosive substances, Packing group, II, medium danger.

Personal Protection

Safety glasses, gloves. Avoid generation of dust.

Safety Phrases

Avoid contact with skin. Avoid contact with eyes.

This information is provided in good faith, for those that wish to use oxalic acid in the treatment of honey bees that are infested with varroa mites.

Originally written by Dave Cushman. Edited by Roger Patterson.

Page created 26/04/2008

Page updated 28/12/2020

Written... 30, 31 October 2005,
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