Rust occurs when iron reacts with oxygen and water to form iron(III) hydroxide.

What is the coefficient of iron in the balanced equation?

Please include steps so that I may learn how to do this problem.

Fe half reaction: 3 H2O + Fe -----> Fe(OH)3 + 3e- + 3 H+
O2 half reaction 4e- + 2 H2O + O2 -------> 4 OH-
12 = LCM: iron half reaction x 4: O2 half reaction x 3
12 H2O + 4 Fe + 6 H2O + 3 O2 -----> 4 Fe(OH)3 + (12 H+ + 12 OH-) 12 H2O
cancel like terms
4 Fe + 6 H2O + 3 O2 -----> 4 Fe(OH)3