Chemical Bonding And Molecular Structure Question 419
Question: The bond dissociation energy of $ B-F $ in $ ~BF_3 $ is $ 646kJmo{l^{-1}} $ whereas that of $ C-F $ in $ CF_4 $ is $ 515kJmo{l^{-1}} $ . The correct reason for higher $ B-F $ bond dissociation energy as compared to that of $ C-F $ is
Options:
A) stronger $ \sigma $ bond between B and F in $ ~BF_3 $ as compared to that between C and F in $ CF_4 $ .
B) significant $ p\pi -p\pi $ interaction between B and F in $ BF_3 $ whereas there is no possibility of such interaction between C and F in $ CF_4 $ .
C) lower degree of $ p\pi -p\pi $ interaction between B and F in $ ~BF_3 $ than that between C and F in $ CF_4 $
D) Smaller size of $ B-atom $ as compared to that of C-atom.
Show Answer
Answer:
Correct Answer: B
Solution:
- The delocalised $ p\pi -p\pi $ bonding between filled p-orbital of F and vacant p-orbital of B leads to shortening of $ B-F $ bond length which results in higher bond dissociation energy of the $ B-F $ bond.
