C6 - Electrolysis

• breaks down substance using electricity
• Ionic compounds can only be electrolyised when in molten or water due to their ions being free to move and carry charge to electorodes.

• Panic - Positive anode, Negative is cathode

• Ions move to opisiteley charged electorde. 
• Cathode - positive ions gain electrons, so are reduced
• Anode - negative ions lose electrons, so are oxidised. 

• Less reactive element is produced at Cathode

• At anode: 
• oxygen given off from discharged hydroxide ions
• a halogen produced if a soloution of halide

• Alumminium oxide - from bauxite, is electrolyised in extraction.
• aluminium oxide mixed with molten cryolite to lower melting point, reducing energy.
• Aluminium forms at cathode
• oxygen forms at anode

• Sodium Chloride soloution (Brine) when electrolysed - Chlorine gas, hydrogen gas given off at electrodes, sodium hydroxide in soloution.
• Hydrogen produced at Cathode as H+ ions are discharged from soloution in prefrence to Na- ions.
• Chlorine produced at anode as Cl- ions are discharged in prefrence to OH- ions.

C6 - Electrolysis.