Acetic acid, also known as glacial acetic acid, chemical formula is CH3COOH. Acetic acid is an organic monic acid and the main component of vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless, hygroscopic solid with a freezing point of 16.6 °C (62 °F). After solidification, it becomes a colorless crystal. Its aqueous solution is weakly acidic and highly corrosive. The steam of acetic acid has an irritating effect on the eyes and nose.