Ethanoic acid, ball and stick molecular model. Also called acetic acid, this carboxylic acid is found in vinegar and gives it its sour taste and pungent smell. It is also used as a preservative and in the production of plastics. This model shows the atoms (spheres) connected by bonds (rods). One double bond is present. The atoms are colour-coded: carbon (black), oxygen (red), and hydrogen (white).