Electrolysis Summary PDF

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ELECTR ELECTROL OL OLYSIS YSIS !

Electrolysis non-spontaneous*reaction* Electricity*is*supplied!to!force!Strongest!Oxidant!to!react!with!Strongest!Reductant!

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Electrolytic Cell

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Comparing Electr Electrolytic olytic and Elect Electrochemical rochemical Cell Cellss

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Predicting Electrode Reactions Example – Molt Molten en Soluti Solutions ons A!Downs!cell!is!a!commercial!electrolytic!cell!the!uses!molten!sodium!chloride!to!produce!sodium!and! chlorine.!Write!the!overall!equation!for!the!cell!reaction!and!calculate!the!minimum!voltage!required! to!drive!this!reaction.! Step*1:!Identify!all!the!species!present! ! o no!H2O!in!molten!solutions!

Step*2:!Highlight!all!present!species!on!an!Electrochemical!Series! Step*3:!Identify!the!strongest!oxidant!and!the!strongest!reductant!

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! ! Step*4:*Write!the!overall!equation!

! ! Step*5:*Calculate!Cell!EMF*

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Non!Spontaneous!-!Must!apply!>!4.07!V!to!drive!this!reaction.! !

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Example – Aqueous Solution Solutionss * Write!the!overall!equation!for!the!cell!occurring!during!the!electrolysis!of!an!aqueous!solution!of! sodium!chloride.!!Calculate!the!minimum!voltage!required!to!drive!this!reaction.! Step*1:!Identify!all!the!species!present! !

Step*2:!Highlight!all!present!species!on!an!Electrochemical!Series! Step*3:!Identify!the!strongest!oxidant!and!the!strongest!reductant!

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! ! Step*4:*Write!the!overall!equation!

! ! Step*5:*Calculate!Cell!EMF*

* Non!Spontaneous!-!Must!apply!>!3.94!V!to!drive!this!reaction.! !

Choosing Water as Reductant or Oxidant

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Factors Affecting Electrolys Electrolysis is

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Detecting the product productss of Electr Electrolysis olysis H2*(g)!!-!pop!test! O2*(g)!!-!re-ignite!a!glowing!splint! Cl2*(g)!-!bleach!smell;!turn!litmus!blue!(base)! ! H+(aq) !!-!!turn!litmus!red!(acid)! OH-(aq)!!-!turn!litmus!blue!(base)! I2*(aq)*-**brown!colour!(Note:!!I-(aq)!is!colourless)* ! !

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Examples of Electrolyti Electrolytic c Reactions Downs Cell – Production of Sodium and Chlorine inert!electrodes! use!molten*electrolyte!rather!than!aqueous!–!water!is!a!stronger!oxidant!than!sodium!ions!

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Membrane Cell – Production of Sodium Hydroxide membrane!used!to!prevent!the!mixing!of!products!formed!at!the!electrodes! only!allows!positive!ions!to!pass!through! results!in!a!very!pure!NaOH!with!little!Cl-!contamination!

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Aluminium Production

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Recharging of Batteries

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Anodising

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Electroplating

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Refining of Copper

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Electrolysis of Water

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