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InterviewSolution
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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 comparad to that of C - F isA. smallar size of B-atom as compared to that of C-atomB. stronger `sigma`-bond between B and F in `BF_(3)`as compared to that between C and F in `CF_(4)`C. significant `ppi-ppi` interaction between B and F in `BF_(3)` whereas there is no possibility of such interaction between C and F in `CF_(4)`D. lower degree of `ppi-ppi` interaction between B and F in `BF_(3)` than between C and F in `CF_(4) ` |
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Answer» Correct Answer - C The empty `2p_(z)` orbitals of B which is not involved in the hybridisation can accept an electron pair from a full `2p_(z)` orbitals of any F-atom , formaing ` pi`-bond . Thus , B-F bond length becomes shorter. Hence, bond is stronger and dissociation energy is higher . |
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