Problem: Consider the following reactions and their heats of combustion.With the above information and your knowledge of alkenes, select the statements that are TRUE.

FREE Expert Solution

Hyperconjugation allows adjacent -R groups (mostly C-C and C-H σ-bonds) to create shared molecular orbitals with π-bonds, stabilizing the bond.



So basically, the more –R groups attached to the double bond, the more stable the double bond will be.

Specifically, when it comes to di-substituted bonds, the order os stability is gem > trans >  cis.

  • trans > cis due to steric hindrance. Groups have less freedom of movement in the cis position.
  • gem > trans due to better hyperconjugation.


The higher heat of combustion, the lower stability.

  • Ignore negative because the energy is stated as a change in enthalpy.
  • The negative stands for energy released. 
  • higher heat of combustion means a higher number.


Analyze each statement:


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Problem Details

Consider the following reactions and their heats of combustion.

With the above information and your knowledge of alkenes, select the statements that are TRUE.

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