In the series ethane, ethylene and acetylene, the C-H bond energy is
a.)the same in all the 3 compounds
b.)greatest in ethane
c.)greatest in ethylene
d.)greatest in acetylene
Dear student
Please find the solution to the asked query:
The strength of the C-H bond depends upon the hybridisation of the Carbon atom.
In the formation of a sp hybrid orbital [in acetylene, HCCH: one 2s orbital and two hybrid orbitals are involved , so the percent s character is 50%
in the formation of a sp2 hybrid orbital[in ethylene CH2=CH2]: one 2s orbital and three hybrid orbitals are involved, so the % s character is 33%
in the formation of a sp3 hybrid orbital[in ethane , C2H6]: one 2s orbital and four hybrid orbitals are involved, so the % s character is 25%
A 2s- orbital keeps the electron density closer to the nucleus compared to the 2p orbital. So as the percentage s character increases, the hybrid orbital holds the electron closer to the nucleus and the bond becomes shorter and stronger.
Thus the C-H bond is strongest in acetylene, thus the C-H bond energy will be greatest in acetylene.
Hence option d is the correct answer.
Hope this information will clear your doubts regarding the topic. If you have any other doubts please ask here on the forum and our experts will try to solve them as soon as possible.
Regards
Please find the solution to the asked query:
The strength of the C-H bond depends upon the hybridisation of the Carbon atom.
In the formation of a sp hybrid orbital [in acetylene, HCCH: one 2s orbital and two hybrid orbitals are involved , so the percent s character is 50%
in the formation of a sp2 hybrid orbital[in ethylene CH2=CH2]: one 2s orbital and three hybrid orbitals are involved, so the % s character is 33%
in the formation of a sp3 hybrid orbital[in ethane , C2H6]: one 2s orbital and four hybrid orbitals are involved, so the % s character is 25%
A 2s- orbital keeps the electron density closer to the nucleus compared to the 2p orbital. So as the percentage s character increases, the hybrid orbital holds the electron closer to the nucleus and the bond becomes shorter and stronger.
Thus the C-H bond is strongest in acetylene, thus the C-H bond energy will be greatest in acetylene.
Hence option d is the correct answer.
Hope this information will clear your doubts regarding the topic. If you have any other doubts please ask here on the forum and our experts will try to solve them as soon as possible.
Regards