NTA Abhyas JEE Main2020ChemistryChemical Bonding and Molecular StructurePractice
The Bond dissociation energy of B − F in BF 3 is 646 kJ mol − 1 whereas that of C − F in CF 4 is 515 kJ mol − 1 . The correct reason for higher B − F bond dissociation energy as compared to that of C − F is
Options
- ASmaller size of B atom as compared to that of C atom
- BStronger σ bond between B and F in BF 3 as Compared to that between C and F in CF 4
- CLower degree of pπ-pπ interaction between B and F in BF 3 than that between C and F in CF 4
- DSignificant pπ-pπ interaction between B and F in BF 3 whereas there is no possibility of such interaction betw
Correct answer
D. Significant pπ-pπ interaction between B and F in BF 3 whereas there is no possibility of such interaction betw
Step-by-step solution
In BF 3 , , B is sp 2 hybridised and has a vacant 2p -orbital which overlaps laterally with a filled 2p -orbital of F forming strong pπ-pπ bond. However in CF 4 , C does not have any vacant p -orbitals to undergo p -bonding. Thus BE B − F   >   BE C − F .