The H of hydrogenation is the heat liberated when a compound undergoes catalytic hydrogenation. Consider the H

The ΔH° of hydrogenation is the heat liberated when a compound undergoes catalytic hydrogenation. Consider the ΔH° values for hydrogenation of the following three alkenes: 3-methyl^-1-butene, 2126.8 kJ mol^-1 (230.3 kcal mol^-1); 2-methyl-1-butene, 2119.2 kJ mol^-1 (228.5 kcal mol^-1); and 2-methyl-2-butene, 2112.6 kJ mol^-1 (226.9 kcal mol^-1).

(a) Draw an energy diagram in which the three alkanes are placed on the same energy scale along with 2-methylbutane.

(b) Use these data to rank the three alkenes in order of stability, most stable first. Explain how you reached your conclusion.

(c) By how much do the heats of formation of the three alkenes differ? Explain.

(d) Explain why this stability order is expected.