1. Determination of Fe
SMK Negeri 13 Bandung

2. Procedure
Weigh out accurately sufficient of the sample to contain 140 mg of Iron, rinse into a 500mL beaker covered with a clock glass and provided with a stirring rod.
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4. Keep the resultant solution not more than 50 mL
Repeat the rinsing process until the weighing bottle is clean with a few more water.
Keep the resultant solution not more than 50 mL
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5. Add l0 mL of dilute hydrochloric acid (1 : 1) followed by about 1 or 2 mL of concentrated nitric acid
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6. Heat the mixture and boil gently for several minutes until the of the solution changes to intense yellow. Test the oxidation completeness with 1-2 drops of ammonia solution
Rinse down the sides of the beaker and the clockglass, and dilute to 200 mL. Heat the solution to boiling.
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7. Add to the resultant hot solution (about C) filtered dilute ammonia solution (1 : 1) drop wise and with stirring until the mixture is faintly alkaline .
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8. Heat the solution and boil for 1 minute
Heat the solution and boil for 1 minute. After the precipitate has settled, pour the supernatant into a fitted filter paper on a funnel.
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9. Add 50 mL of washing solution (hot 1% NH4NO3), stir and let the precipitate settle. Pour the supernatant into filter paper.
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10. Clean the beaker glass with the policeman
Repeat the washing process with another 50 mL of washing solution until the filtrate is chloride free
Clean the beaker glass with the policeman
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11. Dry and char the filter paper
When the moisture has been expelled, the flame is increased slightly so as to carbonize the paper slowly.
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12. When the paper has completely carbonized and vapors are no longer evolved, the flame is moved to the back (bottom) of the crucible and the carbon slowly burned off while the flame is gradually increased.*
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13. After all the carbon has been burned away, the crucible is covered completely (if desired, the crucible may be placed in a vertical position for this purpose) and heated to the required temperature by means of a Bunsen burner.
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14. When the ignition is ended, the flame is removed and, after 1-2 minutes, the crucible and lid are placed in a desiccator containing a suitable desiccant and allowed to cool for minute
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15. The crucible and lid are then weighed.
The crucible and contents are then ignited at the same temperature for minutes, allowed to cool in a desiccator as before, and weighed again.
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16. Calculation Mass of Fe3+ = 2 x Ar Fe x mass of residue Mr Fe2O3
% Fe = Mass of Fe3+ x 100 %
Mass of sample
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