Transition elements

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I am doing my chem investigation on the percentage of copper in coins, and some of the coins contain Fe³⁺ ions. I know that excess ammonia is needed to remove the iron(III) ions, but please can you give me an equation that shows this reaction between the iron and the ammonia?

Ulex replies
 
Copper ions form a soluble complex with ammonia which does not affect the analysis method. Iron(III) ions do not complex with ammonia; instead, because ammonia solution is alkaline, iron(III) hydroxide is precipitated.
 
Fe³⁺(aq) + 3OH^-(aq) -> Fe(OH)₃ (s)

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updated: 16 February 2005