About chemical cell

[dttom]

In a chemical cell if we use copper as the anode and silver as the cathode and sulphuric acid as electrolyte.

Then if any current occurs, the reaction will be:

Cu + 2H+ -> Cu2+ + H2

but it doesn't seem logical, can Cu replace H+?

Or if the set up as the above, any occur will occur and what's the reason?

[woelen]

In a chemical cell if we use copper as the anode and silver as the cathode and sulphuric acid as electrolyte.

Then if any current occurs' date=' the reaction will be:

Cu + 2H+ -> Cu2+ + H2

but it doesn't seem logical, can Cu replace H+?

Or if the set up as the above, any occur will occur and what's the reason?[/quote']

Nothing will happen with this setup. You don't get a spontaneous reaction in which copper replaces hydrogen. If such a reaction does not occur locally, then it also cannot occur in a distributed environment.

 

If you want a current to flow, then the electrodes need to be capable of spontaneous reaction, e.g. a zinc electrode and a copper electrode, combined in a cell with the zinc in a zinc-salt solution and the copper in a copper salt solution and a salt bridhe in between. Then the net reaction will be

 

Zn + Cu(2+) ---> Zn(2+) + Cu.

 

This is a reaction, which also occurs locally spontaneously. In the cell-setup electrons flow from the zinc electrode to the copper electrode.

 

Another setup is a car-battery, with two electrodes made of mainly lead. One of these consists of plain lead, the other is coated with PbO2. The PbO2 is reduced to PbSO4 and the Pb is oxidized to PbSO4 and this process also allows electrons to flow from the lead plate to the PbO2-caoted plate. As you see, the net reaction is that PbO2 oxidized Pb, which also would occur locally.