What is Oxalic Acid and what is it used for


Oxalic acid, also known as ethanedioic acid is a dicarboxylic acid with the formula H2C2O4 . It is a colourless crystalline solid that easily dissolves in water. In terms of acid strength, it is about 3,000 times stronger than acetic acid. It exists as the dihydrate salt.

  • CAS No: 6153–56–6
  • EINECS No: 205–634–3
  • Formula: HOOCCOOH.2H2O
  • MOL Wt: 126.07
  • Oxalic acid: 99.63%
  • Sulphate: 0.07%
  • Chloride: 0.004%
  • Fe: 0.0014%
  • Pb: 0.0006%
  • Toxicity: Oral rat LD50: 7500 mg/kg
  • Physical state: white crystals
  • Melting Point: 101 – 102 C
  • Boiling Point: 149 – 160 C (sublimes)
  • Specific gravity: 1.6–1.7
  • Solubility: 1g/7ml
  • Vapour density: 4.4
  • Flash point: 163 C

Where to use Oxalic Acid

  • Wood bleach – To bleach old and stained wood removing tannin stains and water stains
  • Rust removal- in removing rust on boats, in automotive shops and in restoring antiques
  • in rust stain removal without harming Gel coat, fibre glass, steel and other metal surfaces
  • for pre-treating stainless steel
  • in preparing & polishing stones & marble
  • in restoring furniture
  • by Beekeepers – a 6% solution of oxalic acid in sugar can protect against the parasitic Varroa mite

How to use Oxalic Acid

Prepare a solution by dissolving 60g of oxalic acid in 1 litre of water, apply to stain or rust and allow to work for 20–30 minutes. Always rinse thoroughly with clean water. For wood bleaching it is recommended to neutralize after treatment with a borax solution (3 tablespoons of borax dissolved in 1 litre of water)

Health & Safety:

EU Classification Symbol: Xn

R: 21/22
S: (2-)24/25

Harmful if swallowed.
Causes severe skin burns and eye damage.
May cause respiratory irritation.

UN Hazard Class: 8
UN Pack Group: III

Where to Buy Oxalic acid dihydrate on line in the UK



About mistralhowto

formulation chemist

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