Which method can be used to differentiate between an aldehyde and a ketone?

The ability to differentiate between an aldehyde and a ketone lies primarily in the behavior of these compounds when reacted with oxidizing agents. Aldehydes can be readily oxidized to carboxylic acids, whereas ketones are generally more stable and do not undergo oxidation under similar conditions. This fundamental difference allows for a chemical test using oxidizing agents to distinguish between the two functional groups.

When an oxidizing agent, such as Tollens' reagent or Fehling's solution, is added to an aldehyde, a visible change occurs — typically the formation of a carboxylic acid along with a color change or precipitate. In contrast, a ketone will not react in the same way; it will remain unchanged when exposed to these oxidizing agents. Thus, the reaction with oxidizing agents is a reliable method for distinguishing between aldehydes and ketones based on their contrasting reactivity.

Other methods, such as solubility tests, colorimetric analysis, and pH testing, do not provide a clear and distinct differentiation between these two classes of compounds since they can overlap in solubility and acidity/alkalinity characteristics. Therefore, using oxidizing agents is the most effective means of achieving this differentiation