Copper

[potterfan3]

We have been looking at the purification of copper via electrolysis in chemistry and it left me wondering "how did they get the pure copper for the negative electrode in the first place?" My teacher says it came from outer space

[Beohthram]

well in the copper chloride solution surrounding the electrodes, the copper ions in the solution are positive (Cu2+) and the chloride ions are Cl-. the copper deposits on the negative electrode because the opposite polarities attract each other i.e. the positive copper ions are attracted to the negative electrode. the negative chlorine ions should be attracted to the positive electrode releasing chlorine gas. hope that was of help.
unless you just wanted to know where they got the copper from to make the solution. in that case they probably just got a lump of copper from somewhere. then they just react it with chlorine gas.

[brachiopod]

You could actually use, say, a carbon electrode for the cathode, but this would mean having to separate it from the pure copper deposited around it at the end of the the electrolysis.

By using some of the previously purified copper for the next cathode, separation of the different materials is unnecessary when the next electrolysis is complete.

The impure copper, of course, is obtained by smelting from copper ores, such as cuprite, (copper oxide), chalcocite (copper sulphide), and chalcopyrite (an iron/copper sulphide).

[CT]

Initially it did come from space. All heavier elements are formed in supernovae, as nothing heavier than iron is formed by fusion in stars. The material from a nearby supernova must have collected in the gas cloud that was where our solar sytem was located during the formation of the planets. This eventually becomes mixed in with all the other elements making the earth. Then as brachiopod has put, we refine the copper from different ores.

[Hamish]

The potential needed to reduce a metal salt to the metal is very specific. If you take an impure copper solution and apply a potenial wich will only reduce the copper ions, they will plate out on the annode - if its carbon you can then dissolved it in v pure HCl to get high purity copper chloride. The really pure stuff in my catalogue is 99.999% and costs about 2 pounds a gram. copper sulfate is about the same, iron(II) chloride is about 17 pound a gram at the same purity