AP Chemistry
9.7 Coupled Reactions
9.3 Gibbs Free Energy and Thermodynamic Favorability
In industrial iron smelting, solid iron(III) oxide is reduced to iron. The thermodynamically unfavorable decomposition of \(\text{Fe}_2\text{O}_3\text{(s)}\) is coupled with the oxidation of carbon monoxide gas, as represented by the following thermochemical equations at \(298 \text{ K}\):
\[\text{Fe}_2\text{O}_3\text{(s)} \rightarrow 2\text{ Fe(s)} + \dfrac{3}{2}\text{ O}_2\text{(g)} \quad \Delta G^\circ_{298} = +740\text{ kJ/mol}_{rxn}\]
\[\text{CO(g)} + \dfrac{1}{2}\text{ O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} \quad \Delta G^\circ_{298} = -260\text{ kJ/mol}_{rxn}\]
Based on the information above, what is the value of \(\Delta G^\circ_{298}\) for the overall coupled reaction represented below?
\[\text{Fe}_2\text{O}_3\text{(s)} + 3\text{ CO(g)} \rightarrow 2\text{ Fe(s)} + 3\text{ CO}_2\text{(g)}\]
\[\text{Fe}_2\text{O}_3\text{(s)} \rightarrow 2\text{ Fe(s)} + \dfrac{3}{2}\text{ O}_2\text{(g)} \quad \Delta G^\circ_{298} = +740\text{ kJ/mol}_{rxn}\]
\[\text{CO(g)} + \dfrac{1}{2}\text{ O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} \quad \Delta G^\circ_{298} = -260\text{ kJ/mol}_{rxn}\]
Based on the information above, what is the value of \(\Delta G^\circ_{298}\) for the overall coupled reaction represented below?
\[\text{Fe}_2\text{O}_3\text{(s)} + 3\text{ CO(g)} \rightarrow 2\text{ Fe(s)} + 3\text{ CO}_2\text{(g)}\]
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