CH3COOH – acetic acid – is a colorless liquid with a characteristic pungent odor and sour taste. It is the second-simplest carboxylic acid (after formic acid). Anhydrous (water-free) acetic acid is called glacial acetic acid due to the ice-like crystals it forms at temperatures below 16oC. 3-15% aqueous solutions of acetic acid are called vinegar. It is widely used as a food preservative, condiment, and ingredient in the pickling of vegetables and other products. Vinegar is often produced via the fermentation of ethanol or sugars by acetic acid bacteria. Acetic acid is an important compound used in the production of cellulose acetate for photographic film, polyvinyl acetate for wood glue, and synthetic fibers and fabrics.