Battery effect with Copper & Silver?

[nikhsub1]

A question to you metal intellects: A water block with a silver base and a copper top and a copper rad, how bad will the battery effect be? Would it be the same as aluminun/copper?

[JasonKosi]

where'd my chem textbook go...
The standard electrode potentials in an aqueous solution at 25c... (measured in volts)

Copper = .52
Aluminum = -1.66

With these two metals, one is very likely to become the anode and the other very likely to become the cathode (this likelihood is probably calcuated on an ion-by-ion basis). The difference in potential is about 2.14V.

Copper = .52
Silver = .80

With these two metals, the likelihood is much less as the difference in potential is only .28V

You'll probably still see some electron/ion swapping (therefore, mild corrosion), but nowhere near the rate at which you'll see it with a Cu/Al system.

One thing you will want to consider is how these two metals corrode. When iron corrodes, you get a red, flaky, dusty material that has no structural strength (hence why it is bad when iron/steel corrodes). However, when chromium corrodes, it combines with oxygen to create cromium oxide which is a very shiney and tough substance (hence why you see lots of chrome on blinger cars :) ). Titanium oxide on the other hand produces a very white substance that is used in paint.

My point is, that silver oxide or copper oxide (or possibly a number of other silver or copper ionic compounds depending on what you put in your water) could do unexpected things (though if my grandparents good silver dinner service is any indication, this won't be an issue, tarnish is just oxidation).

If you want, I could try to dredge up all my memories (nightmares?) regarding electromotive force..... *shudder*

[nikhsub1]

JasonKosi, this was EXACTLY the sort of smart scientific answer I was looking for, Thank You!

[550M]

The corrosion shouldn't be too bad. The corrosion should form a protective layer and keep more ions from going into the solution. Are the copper and silver parts up against eachother, or will they be seperated by hoses or something else? This brings back horrible horrible memories of chem 102 :eek:

[nikhsub1]

Originally posted by 550M
The corrosion shouldn't be too bad. The corrosion should form a protective layer and keep more ions from going into the solution. Are the copper and silver parts up against eachother, or will they be seperated by hoses or something else? This brings back horrible horrible memories of chem 102 :eek:
They will be touching, the TOP is copper, the BASE is silver.

[JML]

Don't additives like Water Wetter prevent such things from happening anyway? :confused:

[550M]

well having them up against eachother isn't the best, but at least that way you can take them apart to clean them if you need to. i would think that if you put anything into solution in the water it would slow corrosion, because then the metals wouldn't go into solution. i'm not sure about that though, it just sounds good:D I do know that it will get worse if you use automobile coolant, that makes corrosion worse. If you have more than 50% mix of that with water it starts to do some wierd stuff too, plus cooling ability gets worse.