Chemistry - Thermochemistry Question with Solution | TestHub

(i) $\mathrm{S}(\mathrm{g})+\frac{3}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{SO}}_3(\mathrm{g})+2x$ kcal $\Delta {\mathrm{H}}_1$ (ii) ${\mathrm{SO}}_2(\mathrm{g})+\frac{1}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{SO}}_3(\mathrm{g})+y$ kcal $\Delta {\mathrm{H}}_2$ (i) - (ii) $\begin{array}{rl}& \mathrm{S}(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{SO}}_2(\mathrm{g})\Delta \mathrm{H}\\ & \Delta \mathrm{H}=\Delta {\mathrm{H}}_1-\Delta {\mathrm{H}}_2\\ & =-2x-(-y)=(y-2x)\mathrm{kcal}\end{array}$