Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: cableguy on 29/11/2012 11:16:38

Title: What is the chemical equation for the rusting reaction of iron in salt water?
Post by: cableguy on 29/11/2012 11:16:38
Hi, I've been smashing my head against the desk trying to figure this out, but to no avail. What is the equation of iron rusting in tap water against salt water?
Title: Re: What is the chemical equation for the rusting reaction of iron in salt water?
Post by: Kryptid on 01/12/2012 00:41:44
Here's a link you might find interesting: http://corrosion-doctors.org/Experiments/rust-chemistry.htm (http://corrosion-doctors.org/Experiments/rust-chemistry.htm)

And this: http://www.madsci.org/posts/archives/2005-12/1134348446.Ch.r.html (http://www.madsci.org/posts/archives/2005-12/1134348446.Ch.r.html)

Dissolved salt would act as an electrolyte, the net effect being to speed up the reaction because of the increase in electrical conductivity of the solution.
Title: Re: What is the chemical equation for the rusting reaction of iron in salt water?
Post by: cableguy on 03/12/2012 23:33:19
Thank you, mate. Got another question, how about if I wrap piece of copper wire around the iron? My experience is the iron would rust faster and I assume that's because iron is more reactive than copper, so it will release electrons easier:
Fe -> Fe2+ + 2e-
But where do the electrons go? Usually, I'd say:
Cu2+ + 2e- -> Cu
That would bring me to the copper's involvement in all of this, but where did the copper ions come from?
Title: Re: What is the chemical equation for the rusting reaction of iron in salt water?
Post by: Kryptid on 04/12/2012 06:30:42
According to the first link, the electrons released by the iron would be consumed by the hydrogen ions and oxygen in solution to produce water.

You may also be interested in this: http://en.wikipedia.org/wiki/Galvanic_corrosion (http://en.wikipedia.org/wiki/Galvanic_corrosion)