Explain how the Kekulé model of benzene is contradicted by the hydrogenation enthalpies of ethene and benzene

The Kekulé model of benzene consists of a 6 membered ring with 3 double bonds. This would imply a hydrogenation enthalpy very similar to that of ethene, since double bonds react with hydrogen in a similar statement way, however we find that the enthalpy is less positive than expected. This is due to the delocalisation of the electrons in the pi bonds spreading the electron density across the ring, leading to benzene being more stable than predicted, as there is less electron density in an aromatic bond than a normal C=C bond. (Also I would draw the resonance structures of the Kekulé model demonstrating the delocalisation)

Answered by Lukas M. Chemistry tutor

1005 Views

See similar Chemistry KS3 tutors

Related Chemistry KS3 answers

All answers ▸

Give the general formula for the alkane homologous series and explain their similarities


CH3OH + 1.5O2 -> CO2 + 2H2O. Using the information from Table 10 of the Data Booklet, determine the theoretical enthalpy of combustion of methanol.


Is sodium deposited during the electrolysis of brine?


Calculate the enthalpy of combustion of 1 mol of ethanol using mean bond enthalpy (kJ/mol) data: C-C (347), C-H (413), C-O (358), O-H (464), O=O (498), C=O (805)


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