What is the IUPAC name for CH3CH2COOH?

The compound CH3CH2COOH is a carboxylic acid, indicated by the presence of the –COOH functional group. To determine its IUPAC name, we need to identify the longest continuous carbon chain that contains the carboxylic acid group.

In CH3CH2COOH, there are three carbon atoms in the longest chain. The chain can be numbered starting from the carbon of the carboxylic acid group to give it the lowest number possible. This results in the following structure:

1. The carboxylic acid carbon (C1).

2. The next carbon in the chain (C2).

3. The third carbon connected (C3).

Since there are three carbon atoms in total, the name is derived from the base name for three carbons, which is "propane." The presence of the carboxylic acid functional group changes the suffix from -ane (alkane) to -oic acid, leading to the name "propanoic acid."

Understanding this structure and naming convention confirms that the name is indeed propanoic acid, making it the correct choice.