Acetic acid, also known as acetic acid, glacial acetic, chemical-type CH3COOH, is an organic one-yuan acid and short chain saturated fatty acids, the source of sour and pungent odor in vinegar. Pure anhydrous acetic acid (glacial acetic acids) is a colorless hygroscopic solid, the solidification point is 16.7 ℃ (62℉), solidified after the colorless crystal. Although it is a weak acid based on the dissociation capacity of acetic acid in aqueous solution, acetic acid is corrosive, and its vapor has an irritating effect on the eye and nose. Acetic acid is a simple carboxylic acid, composed of a methyl carboxyl group, is an important chemical reagent. In the chemical industry, it is used to make polyethylene two ester, the latter is the main part of the beverage bottle. Acetic acid is also used to make vinyl acetate in cellulose and wood adhesives required for film films, as well as many synthetic fibres and fabrics. In the family, dilute acetic acid is often used as a descaling agent. In the food industry, acetic acid is a prescribed acidity regulator in the food additive list E260. The worldwide demand for acetic acid is around 6.5 million tonnes per year. About 1.5 million tonnes are recycled, and the remaining 5 million tonnes are made directly from petrochemical raw materials or through biological fermentation. Acetic acid (ethanoic acid) is both a commonly used name and an official name as stipulated by the International Union of Pure and Applied Chemistry (IUPAC). Commonly known as acetic acid (acetic acid), the name is derived from the Latin expression of vinegar in the word "acetum". Anhydrous acetic acid is at a slightly lower temperature (16.7 ℃), can be converted into a corrosive ice crystals, it is often said that almost anhydrous acetic acid is glacial (glacial acetic acid).