C3 Electrolysis of Molten Ionic Compounds OCR Gateway (9-1)

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  • Created by: Aleena
  • Created on: 12-04-18 15:34
What is the name of the negative electrode?
Cathode
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What type of ions are attracted to the Cathode?
Cations(Positive ions)
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What is the name of the positive electrode?
Anode
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What type of ions are attracted to the Anode?
Anions(Negative ions)
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Can a solid ionic compound be electrolysed?Why?
No because the ions are in fixed positions in a regular lattice structure and can't move-so can't conduct electricity.
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Can molten ionic compounds be electrolysed?Why?
Yes because the ions can move freely & conduct electricity
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At which electrode are the ions reduced?
At the Cathode the cations are reduced
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At which electrode are the ions oxidised?
At the Anode the anions are oxidised
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Why do you extract metals with electrolysis?
Metals more reactive than carbon are extracted using electrolysis e.g.Aluminium
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In what compound do you naturally find Aluminium in?
Aluminium Oxide (Al2O3) Al3+ O2-
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Why is Aluminium Oxide mixed with Cryolite for electrolysis?
Aluminium Oxide has a very high melting point (around 2000*C). When mixed with Cryolite it lowers the MP, so less energy is needed & you saves money
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What are the electrodes made of ?Why?
Graphite (Carbon) because it is a great conductor of electricity & has a high melting point
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What ions are present at the cathode and anode during the electrolysis of Aluminium Oxide?
Cathode:Al3+ Anode:O2- So aluminium ions are being reduced to aluminium atoms. Oxygen ions are being oxidised to oxygen atoms.
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Why must the Anodes be replaced regularly?
Anode must be replaced regularly because oxygen molecules react with Graphite(Carbon) to form Carbon Dioxide gas-due to the high temperature, which starts a chemical reaction
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Give 2 reasons why Electrolysis is so expensive?
1)Electrolysis is expensive because alot of energy is required to melt the compounds like Aluminium Oxide- requires lots of energy 2)Alot of energy is needed to produce the electric current
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During the electrolysis of Lead Bromide, what can you see forming at the electrodes?
Anode:Brown vapour of Bromine gas Cathode: beads of molten lead
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Make sure you memorise the half equations for...
Lead Iodide, Pottasium Chloride & Aluminium Oxide
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Other cards in this set

Card 2

Front

What type of ions are attracted to the Cathode?

Back

Cations(Positive ions)

Card 3

Front

What is the name of the positive electrode?

Back

Preview of the front of card 3

Card 4

Front

What type of ions are attracted to the Anode?

Back

Preview of the front of card 4

Card 5

Front

Can a solid ionic compound be electrolysed?Why?

Back

Preview of the front of card 5
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