i conducted an experiment with an anode (copper strip) and a cathode (a dime). I connected the dime with an alligator wire clip to the negative terminal on a battery, and did the same with the copper strip to the positive terminal. I then immersed the two (without touching) into a solution of copper sulfate for 3 minutes or so, resulting in a copper plating (electroplating) of the coin. I reversed the flow and the copper plating disappeared after time. I understand the electron/ current flow, oxidization, and reduction in the experiment, but what is the purpose of the copper sulfate solution?
to transfer ion, like porous pot and salt bridge........ I think
To provide copper ions for electroplating. The copper solid losses its electrons and becomes copper ions. The copper sulphate already contains moving copper ions. If you were to use water or other medium, electroplating would be quite hard or impossible to carry out. For example, if you use Iron (II) sulphate as the electrolyte, the coin would be electroplated by Iron and copper which you don't want as you only want copper. If you use water, the efficiency of copper to cover the dime is low as the concentration of copper ions in the water would be too little. Also, other metals in the water would instead be attracted to the dime and this would not result in full copper electroplating. If you use copper sulphate, there would only be 4 kinds of ions in the solution, that is, hydrogen ions, hydroxide ions, copper ions and sulphate ions. Negative ions would not be attracted to the dime as they can only give out electrons. hence, Copper ions and Hydrogen ions are attracted to the dime. When hydrogen ions receive electrons, they become hydrogen gas and would not stick to the dime. When copper ions receive electrons, they become copper solid and would electroplate the dime. Thus, by using copper (II) sulphate as the electrolyte, you would get a faster kind of electroplating because of a high abundance of copper ions.
