P6 Flashcards
Cathode
- Reduction occurs here
- electrons are gained
- always happens to metal ions
why do solid ionic structures not conduct electricity?
their ions are strongly bonded and fixed in position so cannot move around
uses of aluminium:
- aeroplanes
- cooking foil
- pans
Difference between ore and rock
An ore is a rock which contains enough metal to be economical to extract
electrolysis of brine:
- brine produces 3 useful products when electrolysed:
- chlorine gas
- hydrogen gas
- sodium hydroxide
- hydrogen at cathode
- chlorine at anode
aqueous solution at anode:
- hydroxide ions from water are often discharged. when hydroxide ions are discharged, you see oxygen gas given off
- this happens unless the solution contains high conc of a halide(group 7) ion if this happens the halide ion is discharged and the halogen is formed
aqueous solutions at cathode:
- hydrogen will be produced if the metal is more reactive than hydrogen
- the metal will be produced if it is less reactive than hydrogen
Anode
- Oxidation occurs here
- electrons are lost
- always happens to non-metal ions
How to break solid ionic structures?
- melt the ionic compound by heating
- dissolve it into a solution
aluminium ore:
- bauxite
- mined by open cast mining, digging directly from the surface
electrolysis of aluminium oxide:
-aluminium oxide is mixed with molten cryolite
to lower its melting point, reducing the energy needed to extract the aluminium
-aluminium at cathode
-oxygen at anode
-carbon anodes are replaced regularly as they gradually burn away as the oxygen reacts with the hot carbon anodes forming carbon dioxide gas
Cons of electrolysis
-Can be expensive
what is electrolysis?
the process of breaking up two ionic compounds using electricity
