Module C2 - Rocks And Metals - Extracting Pure Copper

Copper is often dug out of the ground as an ore called malachite.  In theory, the copper could be extracted by reducing it with carbon (unreactive metals can often be extracted from ores by a process called reduction).  The problem is that copper produce by reduction isnt pure enough fore use in electrical conductors.  And the purer it is, the better it conducts.  So another method is usually used...

1) Electrolysis means "splitting up with electricity".                                                  2)It requires a liquid (called the electrolyte) which will conduct electricity.  Electrolytes are usually free ions dissolved in water.  Copper(11) sulfate solution is the electrolyte used in puryfying copper - it contains Cu2(small two in corner of the u) + ions.                                                                                                           3) The electrical supply acts like an electron pump:

1) It pulls elecrons off copper atioms at the anode, causing them to go into solution as Cu2(small two in corner)+ions.

2) It then offers electrons at the cathode to nearby Cu2(small two in corner)+ions to turn them back into copper atoms. 

3) The impurities are dropped at the anode as a sludge, whilst pure copper atoms bond to the cathode.

4) The electrolysis can go on for weeks and the cathodes is often 20 times bigger at the end of it. 

1) Its cheaper to recycle copper that it is to mine and extract new copper.

2) Recycling copper uses only 15% of the energy that'd be used to mine and extract the same amount.  So recycling copper helps to consrve the world's supply of fossil feuls, and reduces carbon dioxide emissions.