Electrolyisis Flashcards
Facts about electrolysis
- solid ionic compounds can’t conduct electricity
= ions are locked in place and can’t move
When ionic compounds melted or dissolved forces attraction broken and ions free to move
= now conduct electricity
What is an anode
Positive electrode
= lack of electrons
Describe process of electrolysis
- Positive Pb ions attracted to negative electrode
- Pb now gain two electrons to form Pb atoms
= reduction reaction
Why is aluminium oxide mixed with cryolite
Lowers melting point
= reduces energy needed
= saves money
What are anode and cathode made of
Graphite (carbon)
Half equation electrolysis of aluminium oxide
Al3+ + 3e- = Al
Half equation oxidation
O2- = O + 2e-
What must happen to anode regularly
Must be replaced regularly
= oxygen molecules produced at anode react with graphite (carbon)
= forming carbon dioxide gas
Why is electrolysis expensive
Melting compounds such as aluminium oxide requires great deal of energy
A lot of energy required to produce electric current
What happens to water molecules
They ionise to form hydrogen and hydroxide ions
Describe the rule of hydrogen
Hydrogen is produced at the cathode if the metal is more reactive than hydrogen
Half equation of the cathode
Cu2+ + 2e = reduction= Cu
Anode half equation
4OH- = oxidation= O2 + 2H2O + 4e-
What happens to aqueous solution if it contains halide ions
Halogen will be produced at the anode
Use of mixture as an electrolyte
Has a low melting point
= less energy needed
