Iron reacts with steam as shown:
Fe(s) + H2O(g) → Fe3O4(s) + H2(g)
When the equation is balanced with the smallest whole numbers, what is the coefficient of H2O?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 4
A balanced equation has the same number of atoms of each element on both sides (law of conservation of mass).
Fe: 3 atoms in \(\mathrm{Fe_3O_4}\), so write \(\mathrm{3Fe}\)
O: 4 atoms in \(\mathrm{Fe_3O_4}\), so write \(\mathrm{4H_2O}\)
H: \(4\times2=8\) atoms on the left, so write \(\mathrm{4H_2}\)
Balanced: \(\mathrm{3Fe+4H_2O\rightarrow Fe_3O_4+4H_2}\)