Chemistry-Electrolysis

These cards are on electrolysis.

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  • Created by: Lauren
  • Created on: 07-05-12 10:17

Electrolysis

  • Copper is a transistion metal. It is hard, strong and has a high melting point.
  • It is a good conductor of electricity, so it's ideal for drawing out into electrical wires.
  • It can also be made into pipes, and as it's below hydrogen in the reactivity series it doesn't react with water. This makes it great for using in plumbing.
  • The copper produced is impure-and impure copper doesn't conduct electricity very well.
  • So electrolysis is used to purify it, even though it's expensive. This produces very pure copper, which is a much better conductor. 

Electrolysis uses electricity to seperate the metal from the ore. Aluminum is another metal seperated from it's ore in this way. 

Electroylsis and the Half-Equations

Electrolysis means  "Splitting up with Electricity" 

  • Electrolysis is the breaking down of a substance using electricity.
  • It requires a liquid to conduct the electricity, called the electrolyte.
  • Electrolytes are usually free ions dissolved in water, e.g. dissolved salts or molten ionic substances.
  • In either case it's the free ions which conduct the electricity and allow the whole thing to work.
  • For an electrical circuit to be complete, there's got to be a flow of electrons. Electrons are taken away from ions at the positive anode and given to other ions at the negative cathode. As ions gain or lose electrons they become atoms or molecules and are released. 

(http://content.answcdn.com/main/content/img/McGrawHill/Encyclopedia/images/CE221700FG0010.gif)

1) At the cathode, two hydrogen ions accept two electrons become one hydrogen molecule.

2) At the anode, two chloride (Cl-) ions lose their electrons and become one chlorine molecule. 

3) NaOH is left in the solution. 

Electroysis is Used to Purify Copper

  • The purer copper is, the better it conducts, so electrolysis is used to obtain very pure copper.
  • Electrons are pulled off copper atoms at the anode, causing them to go into solution as Cu2+ions.
  • Cu2+ions near the cathode gain electrons and turn back into copper atoms.
  • The impurities are dropped at the anode as a sludge, while pure copper atoms bond to cathode.
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