Using bond energy data, calculate heat of formation of isoprene: 5C(s) + 4H₂(g) → CH₂=C(CH₃)−CH=CH₂ Given C−H, H−H, C−C, C=C and C(s) → C(g) respectively as 98.8 kcal, 104 kcal, 83 kcal, 147 kcal, 171 kcal