Aldehydes and ketones can be distinguished by using.

.The Tollens' test is a reaction that is used to distinguish aldehydes from ketones, as aldehydes are able to be oxidized into a carboxylic acid while ketones cannot. Tollens' reagent, which is a mixture of silver nitrate and ammonia, oxidizes the aldehyde to a carboxylic acid.

.Fehling's solution contains copper(II) ions complexed with tartrate ions in sodium hydroxide solution. On reaction with aldehydes, the blue colour of solution changes to dark red as precipitates of copper oxide are formed whereas there is no reaction with ketones