Chemistry - Thermochemistry Question with Solution | TestHub

Given, (I) ${\mathrm{Fe}}_2{\mathrm{O}}_3(\mathrm{s})+3\mathrm{CO}(\mathrm{g})⟶2\mathrm{Fe}(\mathrm{s})+3{\mathrm{CO}}_2(\mathrm{g})$; $\Delta \mathrm{H}=-26.8\mathrm{kJ}$ (II) $\mathrm{FeO}$ (s) $+\mathrm{CO}(\mathrm{g})⟶\mathrm{Fe}(\mathrm{s})+{\mathrm{CO}}_2(\mathrm{g})$; $\Delta \mathrm{H}=-16.5\mathrm{kJ}$ On multiplying Eq (II) with 2, we get (III) $2\mathrm{FeO}(\mathrm{s})+2\mathrm{CO}(\mathrm{g})⟶2\mathrm{Fe}(\mathrm{s})+2{\mathrm{CO}}_2(\mathrm{g})$; $\Delta \mathrm{H}=-33\mathrm{kJ}$ On subtracting Eq (III) from I, we get $$\begin{array}{r}{\mathrm{Fe}}_2{\mathrm{O}}_3(\mathrm{s})+\mathrm{CO}(\mathrm{g})⟶2\mathrm{FeO}(\mathrm{s})+{\mathrm{CO}}_2(\mathrm{g});\\ \Delta \mathrm{H}=-26.8-(-33)\\ =+6.2\mathrm{kJ}\end{array}$$