Sodium metabisulfite CAS 7681-57-4

Sodium metabisulfite, with the chemical formula Na2S2O5 and CAS number 7681-57-4, is a versatile compound widely used across various fields, including food science, analytical chemistry, and environmental applications.
Chemical Properties
Molecular Weight: 190.11 g/mol
Appearance: It typically appears as a white to yellow powder with a faint sulfur odor.
Solubility: Highly soluble in water, with solubility increasing with temperature (e.g., 45.1 g/100 mL at 0°C and 81.7 g/100 mL at 100°C) .
Applications
Food Preservation: Sodium metabisulfite is commonly used as a food preservative and antioxidant. It prevents enzymatic browning and microbial growth in food products, making it essential in the preservation of fruits, vegetables, and other perishable items .
Analytical Chemistry: In laboratory settings, it serves as a reducing agent and is utilized in iodometric titrations for the determination of various substances, including organic compounds and heavy metals .
Environmental Science: Sodium metabisulfite is employed in water treatment processes to remove excess chlorine and as a dechlorinating agent in wastewater treatment .
Pharmaceuticals: It is also used in pharmaceutical formulations as an antioxidant to stabilize active ingredients and extend shelf life .
Safety and Hazards
Sodium metabisulfite is classified as harmful if swallowed and can cause severe eye irritation. It is important to handle it with care, using appropriate protective equipment to avoid inhalation and skin contact . The compound can decompose when exposed to heat, releasing sulfur dioxide, which is a toxic gas .
In summary, sodium metabisulfite is a crucial compound with diverse applications, particularly in food preservation and analytical chemistry, while also requiring careful handling due to its potential hazards.