C6: Electrolysis >:D Flashcards
What is electrolysis?
The splitting of substances using electricity, used to extract metals that are more reactive than carbon
What is an electrolyte?
An ionic compound that has been either melted or dissolved in water, resulting in the breaking of the electrostatic forces of attraction, and thus the free ions that can now conduct
What is the name of the positive electrode?
Anode
What is the name of the negative electrode?
Cathode
Which ions in an electrolyte attract to which electrode?
Positive ions - cathode (gain electrons, reduction)
Negative ions - anode (lose electrons, oxidation)
What are uses of aluminium?
Aluminium cans
Aircraft
Why is cryolite used in the industrial separation of aluminium?
It lowers the melting point of aluminium, thus reduces the amount of energy needed to melt it and saves money
In extracting aluminium, why are the electrodes made of graphite and why do they need to be replaced?
Graphite is a good conductor of electricity and has a high melting point, but they will oxidise to make carbon dioxide, thus wear away and need to be replenished
What are the half equations for the reduction and oxidation of aluminium oxide?
Cathode - Al3+ + 3e → Al (reduction)
Anode - 2O2- → O2 + 4e (oxidation)
Why is electrolysis expensive?
Melting compounds requires a lot of energy
Energy is required to produce an electric current
What does aqueous mean?
Dissolved in water
When ionised, what do water molecules form?
H+ and OH- ions
What happens if a metal is more reactive than hydrogen is electrolysed?
Hydrogen is produced at the cathode instead of the metal
2H+ + e → H2 (reduction)
What happens at the anode during aqueous electrolysis?
Oxygen is usually produced, with the exception of halides, which are produced instead if they are present
Oxidation = 4OH- → O2 + 2H2O + 4e
Why must the electrodes be inert?
So they don’t react with the solution
