Describe how you test for an aldehyde or ketone and distinguish between the two.

To test for an aldehyde or ketone you would use 2,4-dinitrophenylhydrazine (2,4-DNP). 2,4-DNP mixed with methanol and sulphuric acid is knows as Brady's reagent. If a yellow/orange precipitate is formed when Brady's reagent is added to a mystery solution it indicates the presence of a C=O bond found in aldehydes and ketones. To further distinguish between the two, you would add aqueous sodium hydroxide and aqueous silver nitrate to the original sample until a brown precipitate forms. Then add dilute aquoeus ammnia until the precipitate just dissolves. This combinbation of reagents is known as Tollen's Reagent. If a silver grey solid or mirror like effect is formed, an aldehyde is present. If a ketone is present, there will be no reaction. 

SJ
Answered by Shivali J. Chemistry tutor

36652 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

State why it is initially unexpected for alkenes to undergo electrophilic addition with bromine. Explain why this reaction does indeed occur.


Define the standard enthalpy of formation


describe the structure of graphite


What is the definition of structural isomerism and what are the different types?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning