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Estimation of Iron 2 and Iron 3 in a mixture containing both

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The estimation of iron(II) and iron(III) in a mixture containing both Iron is a transition element. A transition element is an element that forms at least one ion with a partially file d orbital1. Transition metals have several different oxidation states, so can be oxidized and reduced. Oxidizing the Fe2+ will make it Fe3+, and it will lose an electron. Fe3+ e- + Fe3+ Reducing Fe3+ will bring it back to Fe2+, as it will gain an electron. Fe3+ + e- - Fe2+ I have been given a solution containing between 1.1g and 1.3g of iron ions, a mixture of Fe2+ and Fe3+. To work out how much Iron(II) and Iron(III) is in the mixture, I will start with a titration. I will determine the amount of Fe2+ in the mixture originally by titrating with potassium permanganate, and therefore oxidising the Fe2+ to Fe3+. Potassium permanganate, KMnO4, is self indicating, so when the oxidation point is reached, it changes brown. Then I will reduce the Fe3+ back to Fe2+ with zinc powder and work out the amount of Fe2+ in the remaining mixture by titrating the new mixture against approximately 0.1 molar potassium permanganate. ...read more.


Safe handling Wear safety glasses. Emergency Eye contact: Flush the eye with plenty of water. If irritation persists, call for medical help. Skin contact: Wash off powdered zinc with soap and water. If swallowed: Drink plenty of water and call for medical aid if the amount swallowed is substantial. Disposal Consult local rules. Note that powdered zinc may present a fire risk, so should not be disposed of in laboratory waste bins. Protective equipment Safety glasses may be suggested if you will be handling zinc powder. 4 Formula KMnO4 Physical properties Form: dark red to purple crystalline powder Stability: Stable, but decomposes if heated above 150 C. Melting point: ca 150 C (decomposes) Water solubility: moderate, produces solutions which are intensely coloured, even when quite dilute Specific gravity: 2.70 Principal hazards This material is harmful if swallowed or inhaled. It is also harmful if absorbed through the skin. Potassium permanganate is a strong oxidizing agent and may react very exothermically with organic materials. Safe handling Wear safety glasses and keep the solid or solution from contact with the skin.. ...read more.


of Fe2+ there will be, as the purple potassium permanganate will turn the solution colourless when it is all oxidised into Fe3+. After 3 concordant results of the Fe2+ being oxidised to Fe3+ with a certain amount of potassium permanganate, and the iron solution is now Fe3+, adding zinc powder will reduce it all back to Fe2+. A little bit is added sparingly until a colour change appears to brown. Zn + 2Fe3+ = Zn2+ + 2Fe3+ To find the total moles now, of Fe3+, I will titrate 25cm3 of the new solution of all Fe2+ with the approximate 0.1 molar potassium permanganate, the same I used in the first experiment. I will need to use more KMnO4 in the second titration as there is more Fe2+ to oxidise. All of the solution should turn colourless and be oxidised again to Fe3+. The amount of potassium permanganate used will be in proportion to the amount of Fe3+ in the 200cm3 solution. I will then calculate Moles of Fe2+ in second solution - Moles of Fe2+ in first solution = Moles of Fe2+ in complete solution. ...read more.

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