The gas primarily responsible for the acidity of vinegar is acetic acid, which is commonly represented in its molecular formula as CH₃COOH. When vinegar is produced, acetic acid is created through the fermentation of ethanol by acetic acid bacteria. While acetic acid itself is not a gas at room temperature, it can release volatile compounds that contribute to the characteristic smell and flavor of vinegar. The acidity of vinegar is measured in terms of its pH, with a typical range around 2 to 3, which makes it acidic and capable of imparting a sour taste to dishes and serving as a preservative.