SC11c Oxidation and Reduction Flashcards
what is oxidation?
substance gains oxygen
what is reduction?
substance loses oxygen
what is a redox reaction?
oxidation and reduction always take place in the same reaction
do the products or reactants get oxidised and reduced?
reactants
when a metal is extracted from the ore, what happens?
the compound is always reduced to the metal
Lead oxide reacts with carbon to form lead and carbon dioxide.
Explain whether the lead oxide is oxidised or reduced.
The lead oxide is reduced to lead because it loses oxygen.
Copper oxide reacts with hydrogen.
copper oxide + hydrogen → copper + water
Explain what has been oxidised in this reaction.
The hydrogen has been oxidised as it has gained oxygen to form water (H2O).
how is aluminium obtained?
by removing oxygen from aluminium oxide by electrolysis
What happens during the electrolysis of extraction of aluminium?
~aluminium ions are attracted to the cathode where they gain electrons to form aluminium
~the oxide ions are attracted to the anodes where they lose electrons to form oxygen
Aluminium reacts with iron oxide.
2Al + Fe2O3 → 2Fe + Al2O3
Explain what has been oxidised and what has been reduced in this reaction.
~the aluminium has been oxidized as it has gained oxygen to form aluminium oxide ~the ion oxide has been reduced as it has lost oxygen to form iron
when does corrosion happen?
Corrosion happens when a metal reacts with oxygen making the metal weaker over time
What does the corrosion of iron require?
Requires water as well as oxygen
What is the corrosion of iron called?
rusting
what type of metal corrodes rapidly?
more reactive metal
Why is gold used in jewellery?
it doesn’t corrode
