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Extraction of Metals

Extraction of Copper - Purification.

The anode is a block of impure copper.
The cathode is a thin piece of pure copper.

When electricity is passed through the cell
copper is dissolved at the anode by oxidation, Cu²⁺ ions go into solution.

Cu_(s)  -  2e^-       Cu²⁺_(aq)

At the cathode, copper is deposited by reduction.

Cu²⁺_(aq)  +  2e^-       Cu_(s)

As copper ions move from the anode to the cathode
the anode gets smaller as the cathode gets bigger.
This is a redox reaction.

The rate at which the copper ions enter the electrolyte from the anode
is the same as the rate at which the copper ions
leave the electrolyte at the cathode. The concentration of
the copper(II) sulfate solution therefore remains unchanged (continued).

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