Question 12 • Chemistry
To produce CO from CO₂, the second equation must be reversed, changing its enthalpy from −566.0 kJ to +566.0 kJ. Then divide that reversed equation by 2, and divide the third equation by 2, so the CO₂, O₂, and H₂O amounts cancel to give C(s) + H₂O(g) → CO(g) + H₂(g). Thus, the required step listed is reversing the second equation; the enthalpy sign changes when an equation is reversed.
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