Using the required bond energies data, calculate the heat of hydrogenation of ethene to ethane.

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Solution

$C_{2} H_{4} + H_{2} - - \to C_{2} H_{6};$ $Δ H =$ Heat of hydrogenation

$Δ H = (4 B . E_{C - H} + B . E_{C = C} + B . E_{H - H})) - (B . E_{C - C} + 6. B . E_{C - H})$

$Δ H = (4 \times 98.8 + 147 + 104) - (83.1 + 6 \times 98.8)$

$Δ H = 251 - 83.1 - 2 \times 98.8$

$Δ H = - 29.7 k c a l$

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Using the required bond energies data, calculate the heat of hydrogenation of ethene to ethane.

C2H4+H2−−→C2H6; ΔH= Heat of hydrogenationΔH=(4B.EC−H+B.EC=C+B.EH−H))−(B.EC−C+6.B.EC−H)ΔH=(4×98.8+147+104)−(83.1+6×98.8)ΔH=251−83.1−2×98.8ΔH=−29.7 kcal

$C_{2} H_{4} + H_{2} - - \to C_{2} H_{6};$ $Δ H =$ Heat of hydrogenation

$Δ H = (4 B . E_{C - H} + B . E_{C = C} + B . E_{H - H})) - (B . E_{C - C} + 6. B . E_{C - H})$

$Δ H = (4 \times 98.8 + 147 + 104) - (83.1 + 6 \times 98.8)$

$Δ H = 251 - 83.1 - 2 \times 98.8$

$Δ H = - 29.7 k c a l$