Fe2O3•nH2O + 10NaOH 2Na5[Fe(OH)8] + (n-3)H2O
Iron(III) oxide polyhydrate react with sodium hydroxide to produce oktahydroxoferrate(III) sodium and water. Iron(III) oxide polyhydrate and sodium hydroxide - solid. This reaction takes place at a temperature near 75°C in a flow nitrogen.