How can you test for aldehydes and ketones?

Aldehydes can be differentiated from ketones as they give a positive result for the following tests -Tollens' reagent turns from a colourless solution to a silver precipitate.Fehling's solution turns from a blue solution to a red/orange precipitate.If the compound present is a ketone, there will be no further reaction. The reason these tests give the above results for aldehydes is because the reagents are weak oxidising agents, so the aldehydes are oxidised to carboxylic acids and the reagents are reduced, resulting in the observable changes. Ketones cannot be further oxidised, so this is why there is no reaction.