(a) Calculate the enthalpy change for the hypothetical reaction 1-butene $\longrightarrow 2$ -methylpropene. The heats of formation are 1-butene, $-0.30 \mathrm{~kJ} \mathrm{~mol}^{-1}\left(-0.07 \mathrm{kcal} \mathrm{mol}^{-1}\right) ; 2$ methylpropene, $-17.3 \mathrm{~kJ} \mathrm{~mol}^{-1}\left(-4.13 \mathrm{kcal} \mathrm{mol}^{-1}\right)$.
(b) Which butene isomer in part (a) is more stable?