Transition elements
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When aqueous sodium hydroxide is added to a solution of iron(II) sulphate a dark green gelatinous precipitate is formed. Is the colour of the green precipitate changing to brown after hydrogen peroxide is added, due to oxidation of iron(II) ions to iron(III) ions?
The short answer is yes. Hydrated iron(II) hydroxide is usually greenish. Iron(III) hydroxide is a rust red-brown colour.
Hydrogen peroxide is an oxidising agent which readily oxidises iron(II) to iron(III).
Risk assessment
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updated: 23 February 2004
