Chemistry Alchemist
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Electrolysis of 2 Iron electrodes
Quick post 
Im editing a youtube video now and im adding a equation into it but want to know if thats whats actually happening... i dont want to look like a fool
and say something thats not happening.
Im making Iron(III) Oxide with electrolysis with 2 iron nails...
So ive made a salt solution, added the 2 electrodes (both with nails) and then turn on the power... after a while a precipitate of Iron OxyHydroxide
forms which after a while decomposes into Iron(III) Oxide... ive done all that and its finished, but is the following equastions correct?
2NaCl + 2H<sub>2</sub>O --> 2NaOH + Cl<sub>2</sub> + H<sub>2</sub>
What electrode does the iron get oxidized?
Fe + H<sub>2</sub>O --> FeO + H<sub>2</sub>
NaOH + FeO --> FeO(OH) + Na (i know the Na doesnt actually get made, just more NaOH)
2FeO(OH) --> Fe<sub>2</sub>O<sub>3</sub> + H<sub>2</sub>O
Do these equations seem to be right to what actually happened in my experiment?
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liquidlightning
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Iron electrodes are dissolved to Iron (II) Hydroxide which oxidized on air contact to red/brown Iron (III) Hydroxide. No oxides present.
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weiming1998
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Quote: Originally posted by Chemistry Alchemist  | Quick post
Im editing a youtube video now and im adding a equation into it but want to know if thats whats actually happening... i dont want to look like a fool
and say something thats not happening.
Im making Iron(III) Oxide with electrolysis with 2 iron nails...
So ive made a salt solution, added the 2 electrodes (both with nails) and then turn on the power... after a while a precipitate of Iron OxyHydroxide
forms which after a while decomposes into Iron(III) Oxide... ive done all that and its finished, but is the following equastions correct?
2NaCl + 2H<sub>2</sub>O --> 2NaOH + Cl<sub>2</sub> + H<sub>2</sub>
What electrode does the iron get oxidized?
Fe + H<sub>2</sub>O --> FeO + H<sub>2</sub>
NaOH + FeO --> FeO(OH) + Na (i know the Na doesnt actually get made, just more NaOH)
2FeO(OH) --> Fe<sub>2</sub>O<sub>3</sub> + H<sub>2</sub>O
Do these equations seem to be right to what actually happened in my experiment? |
No, I don't think your equations are right. Electrolysis of water containing an inert electrolyte like Na2CO3 causes oxygen to evolve at the anode,
oxidizing the iron electrode and making Fe2O3. The iron will only get oxidized at the anode in water, and this is almost always correct, iron
electrode at the cathode will not produce iron oxide.
But salt water is a bit different. Like you said, chlorine and hydrogen instead of oxygen and hydrogen are produced from the reaction. If the iron is
at the anode, then the chlorine will oxidize the iron into FeCl3 as: 2Fe+3Cl2-->2FeCl3. The consumption of chlorine will lead to an excess of NaOH
in the water, as usually the chlorine from the anode mostly reacts with water, forming a solution of sodium hypochlorite as:
2NaOH+Cl2--->NaOCl+NaCl+H2O. But the chlorine is being consumed by the iron, but also the NaOH is reacting with the formed FeCl3, precipitating a
variety of hydrated iron oxides, mainly FeOOH, or better described as Fe2O3.H2O. Overall approximate equation:
2FeCl3+6NaOH--->Fe2O3.H2O+2H2O+6NaCl, consuming NaOH and restoring NaCl in a cycle that never ends (assuming perfect efficiency) until the iron is
oxidized away.
So, to sum my explanation up, here are the equations:
At the cathode: 2H2O+2e- ---->H2+2OH-. At the anode: 2Cl- ----> Cl2+ 2e-. Oxidation of the iron: 2Fe+3Cl2---->2FeCl3 (idealized).
Precipitation of iron oxide: 2Fe3(+)+6OH- ---->Fe2O3.H2O+2H2O.
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