Acetic acid Acetic acid (CH₃COOH) is a weak organic acid and the main acid responsible for the sour taste and smell of vinegar. IUPAC name: Ethanoic acid Formula: CH₃COOH Molar mass: 60.05 g/mol Appearance: Colorless liquid with a sharp, pungent odor Acidity: Weak acid; pKa ≈ 4.76 Common use: Vinegar, food preservation, chemical manufacturing, and laboratory applications Pure acetic acid: Called glacial acetic acid because it solidifies around 16.6 °C. Ionization in water: