Final answer:
1,3-butadiene has a lower heat of hydrogenation compared to two molecules of 1-butene due to the additional stability provided by conjugation in its double bonds.
Step-by-step explanation:
The question pertains to the comparison of the heat of hydrogenation between 1,3-butadiene and two molecules of 1-butene. The heat of hydrogenation is a measure of the energy released when hydrogen is added across the double bonds of an alkene to form an alkane. This energy correlates with the stability of the alkene - the lower the heat of hydrogenation, the more stable the alkene.
In the case of 1,3-butadiene, we have two double bonds in a conjugated system. This conjugation provides extra stability and thus results in a lower overall heat of hydrogenation compared to two molecules of 1-butene, which each have only one double bond and no conjugation. In essence, conjugation in a molecule like 1,3-butadiene allows for some delocalization of electrons, which increases molecular stability and lowers the overall energy change needed to hydrogenate the molecule.