Structure of Benzene 0.0 / 5 ? ChemistryArenesA2/A-levelOCR Created by: eronwyselwynCreated on: 03-01-15 11:35 What was the Kekule model of benzene? A ring with 3 double bonds constantly flipping between 2 different isomers. 1 of 8 What were the problems with Kekule's structure of benzene? Unreactive compared to alkenes. Bond lengths are all the same, not different. Enthalpy change of hydrogenation is much lower than expected. 2 of 8 What type of reaction takes place between alkenes and bromine? Nucleophilic Substitution 3 of 8 What is the enthalpy change of hydrogentation of cyclohexane? -120kJ per mol 4 of 8 What is the expected and actual enthalpy change of hydrogenation? Expected: -360kJ per mol Actual: -208kJ per mol 5 of 8 What is the delocalisation or resonance energy of benzene? 152 kJ per mol (benzene is 152kJ per mol more stable than the Kekule structure) 6 of 8 What are the lengths of a C=C and a C-C bond C=C 0.134nm C-C 0.153nm 7 of 8 What technique was used to show all the bond lengths in benzene are the same? X-ray studies showed that benzene has a regular hexagon shape. 8 of 8
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