UPSEE Solved Model Paper 1

𝐶6𝐻10(𝑙)+𝐻2(𝑔) → 𝐶6𝐻12 (𝑙)Δ𝐻 = −119𝑘𝐽/𝑚𝑜𝑙
6𝐶(𝑠)+6𝐻2(𝑔) → 𝐶6𝐻12 (𝑙)Δ𝑓𝐻 = −156𝑘𝐽/𝑚𝑜𝑙
6𝐶(𝑠)+3𝐻2(𝑔) → 𝐶6𝐻6 (𝑙)Δ𝑓𝐻 = +49𝑘𝐽/𝑚𝑜𝑙
Two things are needed here,
𝐶6𝐻6(𝑙)+3𝐻2(𝑔) → 𝐶6𝐻12 (𝑙)
and benzene losingall its double donds and forming cyclohexane. Subtracting the first from the second will give us the resonance energy. We flip the formalton of benzene equation, add it to the formation of cyclohexane equation:
𝐶6𝐻6(𝑙) → 6𝐶(𝑠)+3𝐻2(𝑔) Δ𝐻 = −49𝑘𝐽/𝑚𝑜𝑙
6𝐶(𝑠)+6𝐻2(𝑔) → 𝐶6𝐻12 (𝑙)Δ𝑓𝐻 = −156𝑘𝐽/𝑚𝑜𝑙
𝐶6𝐻6(𝑙)+3𝐻2(𝑔) → 𝐶6𝐻12 (𝑙)Δ𝐻 = −205𝑘𝐽/mol
Hypothetical heat of hydrogenation of benzene

Resonance energy = |-357 - (-205)|
= | -152| kJ/mol
= 152 kJ/mol