Chemistry - Thermochemistry Question with Solution | TestHub

Writing the formation reaction

$4\text{C}\left(\text{s}\right)+4\text{H}\left(\text{g}\right)+\text{O}\left(\text{g}\right)\to {\text{C}}_4{\text{H}}_4\text{O}\left(\text{g}\right)$

$\Delta {\text{H}}_{\text{f}}^{\circ }=-62·0={\text{Σ}}_{\text{reac}}\text{BE}-{\text{Σ}}_{\text{product}}\text{BE}$

${\text{Σ}}_{\text{product}}\text{ BE}={\text{Σ}}_{\text{reac}}\text{BE}+62·0$

$=4\times 717+4\times 218+249+62$

$=2868+872+249+62=40 51\text{ KJ}{\text{ mol}}^{-1}$

${\text{Σ}}_{\text{product}}\text{ BE}$is heat of atomization of product into isolated gaseous atoms.

Hence answer is 40.51