Vinegar is a solution of water and acetic acid. This diluted solution can contain 5 percent by volume of acetic acid, also called ethanoic acid. Acetic acid has the chemical formula CH3CO2H, which is a carboxylic acid.
Vinegar is produced from different fruits that contain sugars through the process of fermentation. There are different types of vinegars, such as wine, cider, apple, white, balsamic or rice vinegar. In the United States, the Food and Drug Administration requires that vinegar sold in stores contain at least 4 percent acidity. Distilled white vinegar can have an acidity level that ranges between 4 and 7 percent. Most wine and cider vinegars can have an acidity level that is between 5 and 6 percent.