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Test for the presence of iron

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.