Chemistry - Thermochemistry Question with Solution | TestHub

$2\text{C}(\text{ graphite })+3{\text{H}}_2(\text{g})\to {\text{C}}_2{\text{H}}_6(\text{g})$

${\Delta }_{\text{f}}\text{H}\left({\text{C}}_2{\text{H}}_6\right)=2\Delta {\text{H}}_{\text{comb }}\left({\text{C}}_{\text{gaphite }}\right)+3\Delta {\text{H}}_{\text{comb }}\left({\text{H}}_2\right)$

$-\Delta {\text{H}}_{\text{comb }}\left({\text{C}}_2{\text{H}}_6\right)$

$=-(286\times 2)-(393.5\times 3)-(-1560)$

$=-572-1180.5+1560=-\mathrm{192.5 }\text{kJ}/\text{mole}$