Which one of the following equations is the balanced chemical equation for the given reaction?

Fe + H₂O → Fe₃O₄ + H₂

The correct answer is 3Fe + 4H2O → Fe3O4 + 4H2.

Key Points

• Balancing chemical equations involves adding stoichiometric coefficients to the reactants and products.
  • This is important because a chemical equation must obey the law of conservation of mass and the law of constant proportions, i.e. equal numbers of atoms of each element must be present on the reactant side and product side of the equation.
• The chemical reaction is given as
  • Fe + H_{2 O → Fe3 O4 + H2}
• The balanced chemical equation can be written as
  • Reactant         Products
  • Fe = 1                Fe = 3
  • H = 2                  H = 2  
  • O = 1                  O = 4
• 3Fe + 4H_{2 O → Fe3 O4  + 4H2}