What is the common name for ethanoic acid?

Ethanoic acid is commonly known as acetic acid. This is a well-established name that is widely used in both scientific contexts and everyday language, particularly in reference to vinegar, which contains acetic acid as its main component. The name "acetic acid" derives from the Latin word "acetum," which means vinegar.

Understanding the naming conventions helps clarify why this answer is correct. Ethanoic acid has the formula CH₃COOH, which corresponds to a two-carbon carboxylic acid. The "eth-" prefix in ethanoic refers to its two carbon atoms. However, it's the name "acetic acid" that is more frequently encountered, especially in culinary contexts, which is why it's recognized as the common name.

The other terms listed are names for different carboxylic acids: formic acid is methanoic acid (one carbon), butyric acid is butanoic acid (four carbons), and propanoic acid refers to three carbons. Each of these acids has distinct properties and uses, but they are clearly differentiated from acetic acid by their longer carbon chains. Thus, the link between ethanoic acid and its common name, acetic acid, highlights the need to understand