Electrolysis

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  • Created by: epvan2000
  • Created on: 12-05-15 13:27

Electrodes

Electrode:

  1. An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte or a vacuum)
  2. Electrolysis can only work in molten or liquid compounds because current cannot pass through solid ionic compounds.

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  • A negative electrode is called a 'Cathode'.
  • A positive electrode is called an 'Anode'.

One way which you can remeber which electrode is which, think P.A.N.I.C! It stands for "Positive Anode, Negative Is Cathode"

  • Positive ions are attracted to the Cathode, these are called cations.
  • Negative ions are attarcted to the Anode, these are called anions.

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Electroplating and Redox

Electroplating:

...is coat (a metal object) by electrolytic deposition with chromium, silver, or another metal.

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  • The negative electrode is made of the object to be electroplated.
  • The positive electrode is made of the matal to coat the object with.
  • The electrolyte is the solution of the coating metal.

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Redox Reactions:

An oxidation-reduction (redoxreaction is a type of chemical reactionthat involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.

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  • When an ion loses electrons, it is oxidised
  • When an ion gains electrons it is reduced

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Electrolysis Brine and Lead Bromide

Brine:

Sodium Hydroxide chlorine and hydrogen gas are products of this.

  • Chlorine is used to kill bacteria in pools.
  • The sodium hydroxide is used to bleach for cleaning.
  • Hydrogen is used as fuel.
  • Brine is concentrated sodium choloride solution.
  • The chloride ions move to the anode and chlorine gas is produced.
  • The sodium is more reactive than the hydrogen.
  • The sodium stays in the electrolyte and becomes sodium hydroxide.
  • The positive hydrogen ions moveto the cathode.

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Lead Bromine:

  • Lead bromide solution is the electrolyte.
  • The lead ions are attracted to the cathode.
  • The bromide ions are attracted to the anode.
  • ===> Bromide Gas is given off!

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Extraction of Aluminium

Extraction of Aluminum:

  • Aluminium ore is known as Bauxite. We extract Aluminium from Bauxite and purify it.
  • Aluminium oxide's boiling point is too high so we dissolve it in molten cryolite to lower it. Chaper

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Electrolysis of Aluminium Oxide:

  • Aluminium forms at the cathode and is tapped off.
  • The electrodes are made out of graphite, The anodes need replacing often.
  • The oxygen produced becomes carbon dioxide and burns away the anodes.

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