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

36105 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Order the relative base strength of phenyl amine, methyl amine and methylphenyl amine and outline your reasoning.


Give the electron configuration of fluorine


What is the chemical structure of metal


How does Le Chatelier's Principle allow you to predict the change of the position of equilibrium for an equilibrium reaction?


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences