C-C bond length in the enthane is 154pm while in ethylene it is 134pm.Explain why?

Asked by jgjaigupta1998 | 23rd Aug, 2014, 04:03: PM

Expert Answer:

In ethane there is only single bond between C-C which is sigma bond whereas in ethylene there is a double bond between C=C which consists of a pi-bond formed due to sideways overlap of 2p orbitals of carbon atoms in addition to sigma bond.

pi and sigma bonds together form a double bond which is stronger and shorter than a single sigma bond, thus carbon atoms C=C are closer to each other in ethylene than in ethane C-C

Also, the bond energy of C=C is 610 kJ mol-1 while C-C bond energy of ethane is 370 kJ mol-1. Therefore, carbon-carbon bond lengths are in ethane (154 pm), in ethylene (134 pm) and in acetylene (120 pm).

More bonds make the total bond shorter and stronger.

Answered by Hanisha Vyas | 25th Aug, 2014, 10:55: AM

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