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Oxalic Acid

Oxalic acid, also known as ethanedioic acid, is a colorless crystalline solid with the chemical formula C2H2O4. It naturally occurs in various plants, including rhubarb, spinach, and other leafy greens. Additionally, it can be synthesized through chemical processes involving nitric acid and sodium nitrate.
  • white powder

  • 144-62-7


Product Description

What is Oxalic Acid?

Oxalic acid, also known as ethanedioic acid, is a colorless crystalline solid with the chemical formula C2H2O4. It naturally occurs in various plants, including rhubarb, spinach, and other leafy greens. Additionally, it can be synthesized through chemical processes involving nitric acid and sodium nitrate.

Properties of Oxalic Acid

Physical Properties

Oxalic acid exhibits interesting physical properties. It crystallizes in the form of odorless, transparent crystals that are soluble in water and alcohol. The compound has a melting point of around 189 °C (372 °F) and boils at approximately 365 °C (689 °F). It possesses a strong acidic taste and is highly reactive when in contact with other substances.

Chemical Properties

Chemically, oxalic acid is a strong organic acid that readily undergoes reactions such as oxidation, reduction, and esterification. It reacts with alkalis to form soluble salts called oxalates. Moreover, it can act as a reducing agent in some reactions, demonstrating its versatility in various chemical processes.

Uses of Oxalic Acid

Oxalic acid finds applications in both industrial and household settings due to its unique properties. Let's explore some of its key uses:

Industrial Uses

  1. Metal Cleaning: Oxalic acid serves as an effective cleaner for rust and stains on metal surfaces. It removes tarnish from brass, iron, and steel, making it a valuable component in metal restoration processes.

  2. Bleaching Agent: The compound is utilized in bleaching and dyeing industries to remove color from textiles, wood, and paper. It acts as a reducing agent, breaking down chromophores responsible for coloration.

Household Uses

  1. Cleaning Agent: Oxalic acid is a common ingredient in various cleaning products, particularly for removing rust and hard water stains. It effectively cleans kitchen utensils, tiles, and bathroom fixtures.

  2. Wood Stain Removal: Oxalic acid can eliminate stains caused by water damage or iron deposits on wooden surfaces. It rejuvenates the appearance of furniture and removes blemishes effectively.

Health Effects


While oxalic acid has numerous applications, it is important to handle it with caution due to its toxicity. Ingesting or inhaling high concentrations of oxalic acid can be harmful to human health. The compound may cause irritation to the respiratory system, eyes, and skin. Moreover, it can lead to the formation of calcium oxalate crystals in the kidneys, which may result in kidney stones.

Safety Precautions

To ensure safe handling and minimize health risks associated with oxalic acid, it is essential to follow proper safety precautions:

  1. Protective Gear: When working with oxalic acid, wear appropriate protective gear, including gloves, safety goggles, and a lab coat, to prevent direct contact with the skin, eyes, and clothing.

  2. Ventilation: Ensure adequate ventilation in the working area to minimize inhalation of oxalic acid vapors. If working in a confined space, use a fume hood or work in a well-ventilated environment.

  3. Storage: Store oxalic acid in a secure, labeled container away from incompatible substances. Keep it out of reach of children and pets. Follow local regulations for proper storage and disposal methods.

  4. Dilution: When using oxalic acid solutions, always dilute them according to recommended guidelines. Avoid using high concentrations without proper training or expertise.

  5. First Aid: In case of accidental contact or ingestion, seek immediate medical assistance. Rinse affected areas with plenty of water and remove contaminated clothing. Do not induce vomiting unless instructed by medical professionals.

It is crucial to consult safety data sheets (SDS) and adhere to guidelines provided by the manufacturer or regulatory authorities when working with oxalic acid.

Environmental Impact

Oxalic acid can have environmental implications if not handled properly. Here are some key considerations:

  1. Aquatic Life: High concentrations of oxalic acid in water bodies can be harmful to aquatic organisms. Avoid releasing untreated oxalic acid solutions into drains or natural water sources.

  2. Biodegradability: Oxalic acid is biodegradable under certain conditions. However, it is important to follow proper disposal methods and consult local regulations to prevent environmental contamination.

Production of Oxalic Acid

Oxalic acid can be produced through various methods, including:

  1. Chemical Synthesis: The most common industrial method involves the reaction of nitric acid with sodium nitrate, resulting in the production of oxalic acid.

  2. Natural Extraction: Oxalic acid can be extracted from natural sources, such as plants rich in oxalate content. This method is often employed on a smaller scale.

Alternatives to Oxalic Acid

While oxalic acid offers diverse applications, there are alternatives available for specific purposes:

  1. Metal Cleaning: Alternatives like citric acid, vinegar, or specialized metal cleaners can be used to remove rust and stains from metal surfaces.

  2. Bleaching Agent: Hydrogen peroxide or oxygen-based bleaching agents can serve as substitutes for oxalic acid in bleaching processes.

Oxalic Acid FAQs

Q1. Can oxalic acid be used to clean coffee stains from mugs?

Yes, oxalic acid can effectively remove coffee stains from mugs. However, ensure proper dilution and follow safety guidelines when using oxalic acid for cleaning.

Q2. Is oxalic acid safe to use on all types of metals?

Oxalic acid is generally safe to use on most metals, including brass, iron, and steel. However, it is always advisable to perform a patch test on the metal surface before applying oxalic acid to ensure compatibility and prevent any potential damage.

Q3. Can oxalic acid be used to remove stains from clothing?

Oxalic acid should be used with caution on clothing. It is best to consult the garment's care instructions or seek professional advice before attempting to remove stains using oxalic acid. In some cases, alternative stain removal methods may be more suitable.

Q4. Is oxalic acid harmful to plants?

Oxalic acid, when used in appropriate quantities, can be beneficial for certain plants. However, high concentrations or improper application can have detrimental effects on plant health. It is recommended to follow specific guidelines and consult experts when using oxalic acid in gardening or plant-related applications.

Q5. Are there any natural alternatives to oxalic acid for cleaning purposes?

Yes, there are natural alternatives that can be used for cleaning purposes. Vinegar, lemon juice, and baking soda are commonly used natural cleaning agents that can effectively remove stains and grime from various surfaces.


In conclusion, oxalic acid is a versatile compound with a range of properties, uses, and potential health effects. Its applications span from industrial metal cleaning and bleaching to household cleaning and stain removal. However, caution must be exercised when handling and using oxalic acid due to its toxicity. Safety precautions, proper ventilation, and adherence to storage and disposal guidelines are vital. Considering its potential environmental impact, responsible usage and disposal methods are crucial. Awareness of alternatives also provides options for specific purposes. By understanding oxalic acid comprehensively, we can utilize its benefits while minimizing risks to health and the environment.

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