Using Hess's Law, calculate the standard Gibbs free energy change (ΔG°_rxn) for the reaction: ClO(g) + O3(g) → Cl(g) + 2 O2(g), given the following reactions and their ΔG°_rxn values: 1) 2 O3(g) → 3 O2(g), ΔG°_rxn = +489.6 kJ; 2) Cl(g) + O3(g) → ClO(g) + O2(g), ΔG°_rxn = -101.3 kJ.

• A. +390.0 kJ
• B. +588.2 kJ
• C. -588.2 kJ
• D. -390.0 kJ

Answer: (D)

Verified step by step guidance

1. Identify the target reaction: ClO(g) + O3(g) → Cl(g) + 2 O2(g).
2. List the given reactions and their ΔG°_rxn values: 1) 2 O3(g) → 3 O2(g), ΔG°_rxn = +489.6 kJ; 2) Cl(g) + O3(g) → ClO(g) + O2(g), ΔG°_rxn = -101.3 kJ.
3. Reverse reaction 2 to match the target reaction's products and reactants: ClO(g) + O2(g) → Cl(g) + O3(g). This changes the sign of ΔG°_rxn to +101.3 kJ.
4. Add the reversed reaction 2 to reaction 1, ensuring the stoichiometry matches the target reaction: ClO(g) + O3(g) → Cl(g) + 2 O2(g).
5. Calculate the ΔG°_rxn for the target reaction by adding the ΔG°_rxn values of the modified reactions: ΔG°_rxn = (+489.6 kJ) + (+101.3 kJ).