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.

GN

Related Chemistry A Level answers

All answers ▸

a) How can an element be classified as a transition metal, considering only electronic arrangement? (1 mark) b) In terms of electrons, why is aqueous copper(II) sulphate solution red? (3 marks) c) EDTA is a bidentate ligand. What is a bidentate ligand?(2)


Aminoethane can be prepared by a reduction reaction. Identify a starting compound that can be used to prepare aminoethane by reduction, give the necessary reagent and write an equation for the reaction.


How do I calculate the Gibbs free energy change for a reaction when given the entropy change, enthalpy change and the reaction conditions>


Explain the variation of atomic radius along a period and along a group of the Periodic Table