Electrolysis Flashcards
What does electrolysis do?
Breaks down a substance using electricity
Where do positive ions move towards during electrolysis?
The cathode (negative electrode) - pussytive
Where do negative ions move towards during electrolysis?
The anode (positive electrode)
What do ionic compounds have to do to become electrolysed?
Molten or dissolved in water so ions are free to move and carry their charge to electrodes
What happens at the cathode?
Positive ions gain electrons - reduction
What happens at the anode?
Negative ions lose electrons - oxidation
When the electrolyte is molten what is produced at the anode?
The non-metal
2x^n- —> x2 + 2ne-
When the electrolyte is molten what is produced at the cathode?
The metal
m^n + ne- —> m
When the electrolyte is in solution what is produced at the anode if it does contains halide ions?
The halogen
2x- —> x2 + 2e-
When the electrolyte is in solution what is produced at the anode if it doesn’t contains halide ions?
Oxygen
4OH- —>O2 + 2H2O + 4e-
When the electrolyte is in solution what is produced at the cathode if it’s more reactive than hydrogen?
Hydrogen
2H+ + 2e- —> H2
When the electrolyte is in solution what is produced at the cathode if it’s less reactive than hydrogen?
The metal
mn+ + ne- —> m
How is aluminium oxide extracted?
From electrolysis of the ore bauxite
How would you lower the melting point of aluminium?
Molten cryolite is mixed with aluminium which lowers the energy needed for extraction
What is the anode usually made of?
Carbon
