Chemistry - Thermochemistry Question with Solution | TestHub

Given, (a) $2\mathrm{C}+3{\mathrm{H}}_2⟶{\mathrm{C}}_2{\mathrm{H}}_6;\Delta \mathrm{H}=-21.1\mathrm{kcal}$ (b) $\mathrm{C}+{\mathrm{O}}_2⟶{\mathrm{CO}}_2;\Delta \mathrm{H}=-94.1\mathrm{kcal}$ (c) ${\mathrm{H}}_2+\frac{1}{2}{\mathrm{O}}_2⟶{\mathrm{H}}_2\mathrm{O};\Delta \mathrm{H}=-68.3\mathrm{kcal}$ Now, eqs. $2\times (\mathrm{b})+3\times (\mathrm{c})-(\mathrm{a})$ ${\mathrm{C}}_2{\mathrm{H}}_6+\frac{3}{2}{\mathrm{O}}_2⟶2{\mathrm{CO}}_2+3{\mathrm{H}}_2\mathrm{O}$ Heat of combustion of Ethane $\Delta \mathrm{x}=2(-94.1)$ $\begin{array}{l}+3(-68.3)-(-21.1)\\ =(-188.2)+(-204.9)-21.1\\ =-372\mathrm{kcal}\end{array}$