Which alkene would you expect to have the lowest heat of hydrogenation?
A)I
B)II
C)III
D)IV

Question

Which alkene would you expect to have the lowest heat of hydrogenation? 
A)I 
B)II 
C)III 
D)IV

Quizplus · Accepted Answer

Heat of hydrogenation is the energy released when hydrogen adds across a carbon-carbon double bond. As the number of substituents on the double bond increases, the heat of hydrogenation decreases due to steric hindrance. Among the given options, alkene II has two methyl groups on both carbons of the double bond, causing the highest degree of steric hindrance. Therefore, it is the least reactive towards hydrogenation, and thus has the lowest heat of hydrogenation.

Which Alkene Would You Expect to Have the Lowest Heat