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. 

Answered by Shivali J. Chemistry tutor

33216 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Potassium Chlorate(VII) decomposes to produce Potassium Chloride and Oxygen. Using the following data calculate the enthalpy change of this decomposition: Enthalpy of formation(KClO4) = -430 kJ mol-1, Enthalpy of formation(KCl) = -440 kJ mol-1


What are the reagents used to oxidise an alcohol to a carboxylic acid.


The alkanes and the alkenes are examples of homologous series of compounds. Name 3 properties of a homologous series.


What is the difference between a nucleophile and an electrophile?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences