[delsaber8]

Alright so basically I made a battery using copper, copper nitrate and zinc, zinc nitrate. After doing this and measuring the voltages I was asked to replace one of the electrodes with carbon and vice versa. After that I replaced both electrodes with carbon, I got voltages for all of them and am wondering whether it was just noise or actual electrical potential? Second I am wondering exactly how this would work, how does replacing a solid metal electrode with carbon keep my electrochemical cell working? I understand that carbon and platinum are inert under most conditions but am still a little fuzzy on the whole thing, when it comes to them being electrodes? Finally what would the half reactions look like, I cannot for the life of me figure this out, how do I make a half reaction for a redox reaction if one of the solid electrodes is inert? I am new to the forum so any help would be fantastic, I hope I am posting this in the right section.

[Hunter2]

Think beside your metals you have also some other ions in the solution.  Hydrogen ions are the hint.

[delsaber8]

So are there hydrogen ions in the solution due to impurity in the water, my teacher diluted the copper nitrate with normal tap water so that would explain a lot if it were the case?

[Hunter2]

Not impurity. H₂O contain it already. The salts give acidic reaction in water.

[delsaber8]

ok so theoretically this could work with pure distilled water as well? Also I'm still a little confused when it comes to how these batteries exactly work, why do we have to use the solid zinc with the zinc 2+ ions, why can't I use any random metal will the redox reaction not take place?

[kriggy]

 AFAIK pure distillled water is wery bad at conducting electricity so I think it wont work.
You dont have to use zinc only, you can use many other metals, its probably because Cu/Zn battery is the easy to make. We used |Cu |CuSO4 |KNO3 |Ag2SO4 |Ag |
You have to have your metal electrode embedded into the solution of salt which has same metal ion.
Zn(s) → Zn²⁺(aq) + 2e^- .
Cu²⁺(aq) + 2e^- → Cu(s) .
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s).
Which means that Zn is oxidized and its ions goes into the solution and vice versa with copper. Thats why you use salt bridge or have semipermeable membrane between the two solutions, to allow ions to transfer: NO₃^- which "are left" in solution after reduction  of Cu²⁺ can flow throught the membrane to the other side and maintain electroneutrality. And the electrons flowing through the electrodes are the electricity you measure.
hope it helps

[delsaber8]

ok so if I were to use carbon as an electrode like I said earlier, could I use it as both a cathode or an anode? Also I am still a little confused as to why the metal electrode has to be the same as the metal ions does the anode have to oxidize to replace the departing metal ions?

[delsaber8]

Mods you can lock this one up, I have handed in my lab.

[billnotgatez]

We typically do not lock threads just because someone handed in lab report.
In any case, you may still not have a good grasp of what is going on with the topic you posted and handing in a lab does not stop learning.

[delsaber8]

Fair enough, I was also able to confirm how this battery worked after talking with some class mates and comparing ideas, turns out I had the right idea in the beginning but wound up being mislead by a faulty experiment but by all means if you would like to leave it open that is fine too.