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 Form 4 Chemistry Online Lessons on Extraction of Iron

Test for the presence of iron

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Answer Text:
Iron naturally exist in its compound as #Fe^(2+) or Fe^(3+)# If an ore is suspected to contain #Fe^(2+) or Fe^(3+)# it is;
(i) Added hot concentrated sulphuric (VI)/Nitric (V) acid to free the ions present.
(ii) The free ions are then added a precipitating reagent like 2M sodium hydroxide /2M aqueous ammonia which forms;
I) an insoluble green precipitate in excess of 2M sodium hydroxide /2M aqueous ammonia if #Fe^(2+)# ions are present.
II) an insoluble brown precipitate in excess of 2M sodium hydroxide /2M
aqueous ammonia if #Fe^(3+)# ions are present.


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