raudIIhüdroksiid

Raud(II)hüdroksiid, also known as ferrous hydroxide, is a chemical compound with the formula Fe(OH)2. It is an inorganic substance that appears as a white precipitate when iron(II) salts are added to a solution of a hydroxide. However, it is very unstable and readily oxidizes in the presence of air, turning green and then reddish-brown as it converts to iron(III) hydroxide.

Iron(II) hydroxide is a base, though a relatively weak one. It is insoluble in water, but it can dissolve in acidic solutions due to a neutralization reaction. The preparation of pure iron(II) hydroxide is challenging because of its rapid oxidation. It is typically synthesized by reacting a soluble iron(II) salt, such as iron(II) sulfate or iron(II) chloride, with a strong base like sodium hydroxide or potassium hydroxide in an oxygen-free environment.

FeSO4(aq) + 2NaOH(aq) → Fe(OH)2(s) + Na2SO4(aq)

In aqueous solutions, iron(II) hydroxide exists in equilibrium with dissolved iron(II) ions and hydroxide ions. The compound has found some niche applications, including as a reducing agent in certain chemical processes and historically in some medicinal preparations. Due to its instability and tendency to oxidize, its practical applications are limited compared to other iron compounds. The color change observed upon oxidation is a common indicator of the presence of iron(II) and its subsequent transformation to iron(III).