Register to reply

Oxidation of iron

by tmiddlet
Tags: iron, oxidation
Share this thread:
tmiddlet
#1
Jan11-13, 08:47 PM
P: 26
I've got a question that is bugging me

If I have a concentrated sodium hydroxide solution and electrolyze it with iron electrodes, some of the possible reactions at the positive electrode are
2H2O -> O2 + 4H++4e-. Eo = -1.23 V
4OH- -> O2 + 2H2O + 4e-. Eo = -0.40 V
Fe -> Fe2+ + 2e-. Eo = 0.44 V

and at the negative electrode, the most likely reaction is
2H2O +2e- -> H2 +2OH-. Eo = -0.88 V

Given this information, I would expect to see hydrogen gas at the negative electrode and iron hydroxide at the positive, but when I actually perform it I get oxygen and hydrogen, but no iron hydroxide. Why is this?
Phys.Org News Partner Chemistry news on Phys.org
Chemical biologists find new halogenation enzyme
Protein secrets of Ebola virus
Protein courtship revealed through chemist's lens
Borek
#2
Jan12-13, 02:44 AM
Admin
Borek's Avatar
P: 23,711
Reactions occur in the order from the "easiest" to the "hardest" - so as long as there is water present it will react preferentially.
tmiddlet
#3
Jan14-13, 06:50 PM
P: 26
That's what I thought, but it is much easier to oxidize iron than either water or hydroxide according to the values I found... Why do I not get any iron hydroxide?


Register to reply

Related Discussions
Does natural iron have a denser nucleous then lab made iron? High Energy, Nuclear, Particle Physics 2
Thermochemistry: iron change Biology, Chemistry & Other Homework 1
Redox Titration - Determining the % of Iron II and Iron III Biology, Chemistry & Other Homework 0
How to Separate Rust Iron (Fe2O3) into Ferum/Iron and Oxygen? Chemistry 5
Why iron from a bloomery has less carbon than iron from a blast furnace? General Engineering 0