A ferrate is the anion FeO₄^2- in which iron is in a +6 formal oxidation state (iron VI). A ferrate can be formed by oxidizing iron with strong oxidizing agents under alkaline conditions or in the solid state by heating a mixture of iron filings and powdered potassium nitrate, but it is unstable, especially at neutral to acid pH. Aqueous solutions of ferrates are pink when dilute, deep red at higher concentrations. Ferrate ion is a stronger oxidizing agent than permanganate and will oxidize ammonia to elemental nitrogen.

See also

• Potassium ferrate