Sodium metabisulphite

Sodium metabisulphite (also known as sodium metabisulfite) is an inorganic compound with the chemical formula Na2S2O5. It is a white crystalline or powder solid with a slight sulphur odour. Sodium metabisulphite is used in various industries such as food, pharmaceutical, and water treatment industries due to its preservative and disinfecting properties.

Chemical Properties

Sodium metabisulphite is a salt of sulfurous acid. It is a reducing agent that reacts with oxygen to form sodium sulfate. When dissolved in water, sodium metabisulphite releases sulfur dioxide (SO2), a gas with a pungent and suffocating odour.

Uses

Food Industry

In the food industry, sodium metabisulphite is used as a preservative and antioxidant. It prevents the growth of microbes and preserves the colour of food products. It is commonly used in dried fruits, wines, and molasses.

Pharmaceutical Industry

In the pharmaceutical industry, sodium metabisulphite is used as a preservative in some medications. It is also used in the production of photographic film as a reducing agent to facilitate the development process.

Water Treatment

Sodium metabisulphite is used in water treatment processes to remove excess chlorine. It is also used in the desalination process of seawater.

Health Effects

Exposure to sodium metabisulphite can cause irritation to the eyes, skin, and respiratory tract. Ingestion can lead to symptoms such as nausea, vomiting, and abdominal pain. People with asthma or sulfite sensitivity should avoid products containing sodium metabisulphite.

See Also

• Sulfites
• Preservatives
• Food additives