Oxalic Acid is an organic dicarboxylic acid compound with the chemical formula C₂H₂O₄, found naturally as colorless, odorless crystals. It occurs in certain plants such as rhubarb, spinach, and beetroot and is also industrially produced for use in various sectors. Oxalic acid is particularly valued in industry for its strong metal chelating ability, making it useful in cleaning, textile, leather, and pharmaceutical applications.

Structure

Oxalic acid is the simplest dicarboxylic acid.

Chemical formula: C₂H₂O₄ or (COOH)₂
It consists of two carboxylic acid groups connected directly to each other.
It is typically found as a crystalline solid and exists as a dihydrate (with two water molecules) at room temperature.

Properties

Molar mass: 90.03 g/mol
Melting point: 101–102 °C (for the dihydrate form)
Solubility: Highly soluble in water and alcohol
Appearance: White crystals
pH (aqueous solution): Around 1.3 (strong acid in dilute solution)
Chelation ability: Strong chelator of metal ions like calcium, iron, and magnesium

Applications

Oxalic acid is used in a wide range of industries, including:

Cleaning Industry: Removes rust, ink stains, and mineral deposits
Textile and Dyeing Industry: Used as a bleaching agent and dye fixative
Leather Industry: For cleaning and preparing leather surfaces
Chemical Laboratories: As a standard reagent and chemical agent
Pharmaceutical Industry: In certain drug synthesis and raw material purification
Wood Industry: To lighten wood color and remove metal stains
Beekeeping: Used in controlled applications to combat Varroa mite infestations

Disadvantages

High toxicity: Ingestion or skin contact can be dangerous
Corrosive nature: Causes irritation to skin, eyes, and respiratory tract
Environmental impact: Improper disposal can harm aquatic environments
Risk of kidney stone formation: If consumed, may lead to calcium oxalate kidney stones