10.2 Uses of Electrolysis

Producing Aluminium
Ore: __ (contains Al₂O₃ i.e. a__)
> e__ to electrolyse bc:
>> >__C mp, i__ in H₂O, aq soln cant be made

bauxite, alumina, expensive, 2000, insoluble

Producing Aluminium
> D__ alumina in molten c__ (Na₃AlF₆)
> this __ the temp to 900C

dissolve, cryolite, lowers

Is cryolite a catalyst?

no

Producing Aluminium
> as O₂ is made at the +ve anode, it makes C__, burning the anode
> thus anodes must be r__ frequently

co2, replaced

Producing Aluminium
At the +ve anode:
2O^2- → __ + __

o2, 4e-

Producing Aluminium
At the -ve cathode:
Al³⁺ + __ → Al

3e-

Define electroplating

process where surface of a metal is coated w/ layer of diff metal

In electroplating, the +ve anode is

pure metal to coat obj w/

In electroplating, the -ve cathode is

obj to electroplate

In electroplating, the electrolyte is

aq soln of soluble salt of pure metal

Purifying Copper
> with c__ electrodes

copper

Purifying Copper: w/ copper electrodes
At the -ve cathode:
> Made of __ copper
> goes __ in size
> Cu²⁺ + __ → Cu

pure, up, 2e-

Purifying Copper: w/ copper electrodes
At the +ve anode:
> Made of __ copper
> goes __ in size (as i__ [metals above Cu] oxidised)
> Cu → __ + 2e-

impure, down, impurities, Cu2+