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.