Acetic acid, also known as acetic acid, glacial acetic acid, chemical formula CH3COOH, is an organic monoic acid, as 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). When solidified, it forms a colorless crystal. Its aqueous solution is weakly acidic and highly corrosive.