⇒⇒[ΔHfo]C2H(4)=2×[ΔHsubo]C(s)+2×ΔHH−Ho−1×ΔHC=Co−4×ΔHCHo[ΔHfo]C2H4( g)=(2×710)+(2×436)−611−4×414[ΔHfo]C2H4( g)=25 kJ/mol
Given :
$\begin{aligned}
& \Delta \mathrm{H}_{\text {sub }}^{\ominus}[\mathrm{C}(\text { graphite })]=710 \mathrm{kJ} \mathrm{mol}^{-1} \
& \Delta_{\mathrm{C}-\mathrm{H}} \mathrm{H}^{\ominus}=414 \mathrm{kJ} \mathrm{mol}^{-1} \
& \Delta_{\mathrm{H}-\mathrm{H}} \mathrm{H}^{\Theta}=436 \mathrm{kJ} \mathrm{mol}^{-1} \
& \Delta_{\mathrm{C}=\mathrm{C}} \mathrm{H}^{\Theta}=611 \mathrm{kJ} \mathrm{mol}^{-1}
\end{aligned}$
The ΔHf⊖ for CH2=CH2 is _____ kJmol−1 (nearest integer value)
Held on 3 Apr 2025 · Verified 6 Jul 2026.
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