Which of the following equations is correctly balanced for the reaction between solid iron(III) oxide and hydrogen gas to produce solid iron and water vapor?
Show the answer and explanation
Correct answer
A. Fe2O3(s) + 3H2(g) → 2Fe(s) + 3H2O(g)
Principle or equation
A balanced chemical equation must have the same number of each type of atom on both sides. For iron(III) oxide, the formula is Fe2O3 because iron has a +3 oxidation state and oxide is O2-.
Why this answer is correct
Write the unbalanced equation: Fe2O3 + H2 → Fe + H2O. Balance Fe: 2 Fe on left, so 2 Fe on right. Balance O: 3 O on left, so 3 H2O on right (gives 3 O). Balance H: 3 H2O gives 6 H, so need 3 H2 on left. Final: Fe2O3 + 3H2 → 2Fe + 3H2O. Check atoms: Fe 2=2, O 3=3, H 6=6.
Example
For the reaction of aluminum oxide with hydrogen: Al2O3 + 3H2 → 2Al + 3H2O, balancing similarly.
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