Chemistry - GOC Question with Solution | TestHub

Compare the isomers by gas-phase heats of combustion, which lead to the same ${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$ products. The approximate heat-release magnitudes are 649.33 kcal ${\mathrm{mol}}^{-1}$ for 1-butene, 647.68 for cis-2-butene, 646.90 for trans-2-butene, and 645.19 for 2-methylpropene. The lowest combustion heat corresponds to the lowest-energy isomer, 2-methylpropene, $\mathrm{D}$. Comparing hydrogenation heats alone would require accounting for the different alkane products.