[rickyevolution]

Hi all,

I am an undergraduate mechanical engineering student who is trying to understand some chemistry to complete my project in corrosion control. So any help would be much much appreciated!
(As I am not particularly good at chemistry lol)

The situation is as follows:

- I have got a beaker containing salt water (NaCl solution)
- 2 pcs of steel are put into the beaker and a potential difference is applied
- Since NaCl solution act as an electrolyte, a circuit is completed where I can measure its current (let "x" be the value of this current).
- Hence one piece of steel would rust (anode) and the other piece would stay as it is (cathode)
- By varying the applied potential difference, I could vary the rate of rusting.

The question is now if I introduce a a piece of Zn into the above set up (with known mass and surface area, and without contacting either electrodes directly) what would happen?

(my guess is the Zn oxidises instead of both piece of steel as it is effectively galvanising...Although I think it might depends on the magnitude of the p.d applied)

And can I obtain the effect of the introduction of Zn on the current "x" through theoretical calculations? (Hence I can relate the corrosion rate with the amount of Zn added i.e. more Zn less steel corrosion...but I would like to quantify that using numbers)

I apologise for this long question,  any help would be much much appreciated. It would also be great if you can point me to some reference text so I can learn more about it!

Thank you!

[Borek]

As long as Zn doesn't touch the iron (steel) electrodes, not much will change. It will slowly oxidize, but it would do so even without the steel electrodes and the current.