Question

Consider the following three compounds: HCCH, H2CCH2, and H3CCH3. Part A Order these compounds in order of decreasing carbon-carbon bond strength. Rank the compounds from strongest to weakest carbon-carbon bond. To rank items as equivalent, overlap them.

Answer 1

Answer:

C₂H₂ > C₂H₄ > C₂H₆

Explanation:

Greater the number of bonds, greater is the bond strength and lesser is the bond length. Sigma bonds are stronger than pi bonds.

C₂H₂, ethyne has 1 sigma and 2 pi bonds with sp- hybridization.

The sp orbitals of carbon atoms overlap to give sigma bond and the other two p-orbitals of carbons overlap to give 2 pi bonds.

C₂H₄, ethene has 1 sigma and 1 pi bond with sp²- hybridization.

The sp² orbitals of carbon atoms overlap to give sigma bond and p-orbitals of carbons overlap to give 2 pi bonds.

C₂H₆ , ethane has 1 sigma and 0 pi bond with sp³- hybridization.

The sp³ orbitals of carbon atoms overlap to give sigma bond and there are no p-orbitals left for pi bond to be formed.

Decreasing bond strength order is

C₂H₂ > C₂H₄ > C₂H₆