An Introduction to Glacial Acetic Acid

Glacial acetic acid, chemically known as ethanoic acid with the molecular formula CH₃COOH, is the highly concentrated and anhydrous form of acetic acid, featuring a purity of 99% to nearly 100% and a water content of less than 1%. Distinct from the diluted acetic acid in daily vinegar (only 4%–8% concentration), it is a fundamental and versatile organic chemical raw material widely applied in industrial production, laboratory research and food processing fields.

This colorless, transparent liquid gets its unique name “glacial” from its special physical property. It has a freezing point of approximately 16.7°C; when the ambient temperature drops below this threshold, it solidifies into colorless, ice-like crystalline solids, presenting a glacier-like appearance. With a density of 1.049 g/mL at 25°C and a boiling point ranging from 117°C to 118°C, glacial acetic acid has a strong, pungent vinegar-like odor. It is hygroscopic, capable of absorbing moisture from the surrounding air, and is miscible with water, ethanol and ether, showing excellent solvent performance.

Chemically, glacial acetic acid is classified as a weak acid. It only partially dissociates in aqueous solution and features stable chemical properties under normal temperature and pressure. It can undergo typical carboxylic acid reactions, including esterification, neutralization and oxidation reactions. Notably, its buffer capacity reaches the optimal state at pH 4.75, making it a common buffer reagent in chemical and biological experiments to stabilize solution acidity and alkalinity.

Despite its wide usability, glacial acetic acid requires strict safety management during handling and storage. Its high concentration makes it corrosive; direct contact with human skin, eyes or respiratory mucosa will cause severe irritation and burns. Operators need to wear protective gloves, goggles and breathing protection equipment. It should be stored in a cool, dry and well-ventilated place, isolated from oxidants and alkalis to avoid chemical reactions and safety hazards.