Iron compounds

Iron compounds are chemical compounds that contain iron. Normally the iron is oxidized and bonded with another atom, such as chlorine. The number after the iron indicates the oxidation state of the iron atom.

Iron(II) compounds (in the +2 oxidation state)

These compounds are weak reducing agents. They are normally light colored. They react with oxygen in air. They are also known as ferrous compounds.

• Iron(II) sulfide, a shiny chemical that reacts with acids to release hydrogen sulfide, found in the ground
• Iron(II) sulfate, a blue-green crystalline chemical made by reacting sulfuric acid with steel, used to reduce poisons like chromate in concrete
• Iron(II) chloride, a pale green crystalline chemical made by reacting hydrochloric acid with steel
• Iron(II) hydroxide, a dark green powder made by electrolyzing water with an iron anode, reacts with oxygen and turns brown
• Iron(II) oxide, black, flammable, rare

Mixed oxidation state

These compounds are rare; only one is common. They are found in the ground.

• Iron(II,III) oxide, a black mineral, used as ore of iron, contains iron in the +2 and +3 oxidation state

Iron(III) compounds (in the +3 oxidation state)

These compounds are normally brown. They are oxidizing agents. The are corrosive. They are also known as ferric compounds.

• Iron(III) oxide, rust, red-brown, dissolves in acid
• Iron(III) chloride, poisonous and corrosive, dissolves in water to make dark brown acidic solution. Made by reacting iron with hydrochloric acid and an oxidizing agent.
• Iron(III) nitrate, light purple, corrosive, used in etching
• Iron(III) sulfate, rare, light brown, dissolves in water. Made by reacting iron with sulfuric acid and an oxidizing agent.