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Electrochemistry galvanic cell Doubts?
I have the following doubts in the electrochemical cell topic
1. Why do metals like zinc lose electrons by themselves in galvanic cell (even when there is no other substance to accept those directly) I though it happens only when another element that can accept them is present very close to them as in case of NACL
2. Do Metals like zinc , Silver etc give electrons only in solutions or they give electrons outside the solution (say in vacuum if we take)
3. Why always do we take same salt solution of the salt we take in half cell for example when we consider the reduction half cell where zince gets reduced when in that same oxidation half cell we take zinc sulphate solution only(why only same salt sol not copper sulphate sol)
1 Answer
- jcherry_99Lv 78 years agoFavorite Answer
Let's agree on what a galvanic cell is. Do you mean as in this diagram.
http://en.wikipedia.org/wiki/Galvanic_cell
If you do, then the electrons are going over to the copper (follow the external wire connected to the zinc). The copper gladly accepts those electrons. The copper takes the electrons and gives them to the Cu+2 in solution. The zinc ions fall into the zinc solution. The zinc solution attracts the leftover sulfate ions from the copper solution. Everyone is moving in a circle. electrons through the wire, SO4{2-} over to the Zn ions. Everyone's balanced and happy.
2]
Being in a vacuum should matter. That would only get rid of atmospheric pressure. It would be a pretty volatile metal that would give away electrons in a vacuum.
3]
I can't make out the 3rd question. The grammar seems a little convoluted. Oh wait. I think your question is why can't we use copper sulphate in with the zinc electrode. If that is the question then the answer is you will not get a galvanic cell. The zinc will start reacting directly with the copper sulfate. You will get a direct reaction (single replacement)
Zn + CuSO4 ===> ZnSO4 + Cu. The Cu will fall to the bottom of the solution. No circular action is taking place.
