A question I did in a practice passage gave the reduction potentials of "silver and copper METAL" as positive. They must be talking about the silver and copper ions, right? There's just no way they could be talking about the solid metal itself...
elemental metals can never have a positive reduction potential, correct?
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the way i think of it is the more positive a reduction potential, the more likely it is to happen. if the reduction potential going from Cu(s)----->Cu2+ + 2e- is positive, this indicates that Cu metal IS willing to give those electrons out and become a reducing agent. if the reduction potential of Cu was negative, then the above reaction is not likely to happen, and the reverse will happen making Cu an oxidizing agent.
I'm sure you know all this, but think about it, metals are usually reducing agents so they will usually have positive potentials when giving up electrons. metallic ions are weak oxidizing agents, meaning the reverse will be negative, meaning it will TAKE energy to reduce a Copper ion.
i should clarify also, when they give the reduction potential as positive, are they referring to the Cu(s)----->Cu2+ + 2e- rxn? cause then you would be right.
actually i just looked it up and not ALL metals have a negative reduction potential, copper actually has a positive (.34) reduction potential, making it a good oxidizing agent. when you say the REDUCING potential of something is +.34, you are saying it's ION is spontaneously willing to accept electrons...remember reduction potentials ALWAYS refer to ions and not just pure metals, so even though they were talking about pure metal, it was referring to the ion.
I think they talk about ions, since:
1. Reduction potential is the ability of element to gain electrons.
2. In order for pure metal to accept electrons it has to be reduced to Me- which almost impossible, since metals keep electrons very lose as an "electron gas". However, there are may be exceptions that I am not aware of, like hydrogen can be H- in hydrates.
3. The ions picture is much more clear for example:
Li+(aq) + e- -----> Li(s) -3.05
Cu2+(aq) + 2e- -----> Cu(s) +0.34
which means. Li+ does not accept electron spontaneously, but Cu2+ does.