Question Detail
Question
The standard enthalpy of formation of H₂O(l) at 298 K is -286 kJ mol⁻¹. What is the standard enthalpy change for the reaction: 2H₂O(l) → 2H₂(g) + O₂(g)?
Correct Answer
Option C is the correct answer.
Detailed Explanation
The formation of 1 mol H₂O(l) releases 286 kJ. The decomposition of 2 mol H₂O(l) is the reverse of the formation of 2 mol H₂O(l). ΔH°rxn = -2 × (-286) = +572 kJ.
Hint
Reverse reaction changes the sign of ΔH, and multiply by the coefficient.