Phương trình hóa học :
\((1)Fe + 3C{l_2}\buildrel {{t^o}} \over\longrightarrow 2FeC{l_3}\)
\((2)FeC{l_3} + 3NaOH \to Fe{(OH)_3} \downarrow + 3NaCl\)
\((3)2Fe{(OH)_3}\buildrel {{t^o}} \over\longrightarrow F{e_2}{O_3} + 3{H_2}O\)
\((4)F{e_2}{O_3} + 3CO\buildrel {{t^o}} \over\longrightarrow 2Fe + 3C{O_2}\)