Electrolysis Flashcards
What does discharged mean?
Go from a charged ion to a neutral ion
Where are ions oxidised and where are ions reduced?
Oxidised at anode, reduced at cathode
What forms of solution do you need for an electrolyte?
Aqueous (soluble), molten (insoluble)
What is an electrolyte?
A liquid or solution that contains ionic compound
What ions go to the cathode?
- metal ions
- hydrogen (H+)
Positive ions
What ions go to the anode?
- non metals
- hydroxide (OH-)
Negative ions
What is the purpose of electrolysis?
To split an ionic compound into its neutral atoms
What is the name of the ore from which t aluminium can be extracted from?
Bauxite
What is the purpose of cryolite in the electrolysis of aluminium?
- can dissolve aluminium oxide in molten cryolite (allows you to electrolyse at a lower temp, which uses less energy and is cheaper than electrolysis of a molten solution)
What is the half equation for electrolysis of aluminium oxide at the anode and the cathode?
Anode : 2O(2–) = O2+4e(-)
Cathode : Al(3+) + 3e(-) = Al
What is the equation for electrolysis of aluminium oxide?
2Al2O3 = 4Al+3O2
Why do the positive electrodes need to be replaced?
The carbon electrode reacts with the oxygen made from electrolysis and combusts and burns away so will need to be replaced.
Why is electrolysis expensive?
- need high amounts of electricity constantly
- need high temps
What is the product of the cathode?
The ion of the least reactive element
What is the product of the anode?
OH- unless a group 7 element is discharged
What is an inert electrode?
An un reactive electrode
When is electrolysis used for extracting metals
When the metal is too reactive to be extracted with carbon or if the metal reacts with carbon
What is a redox reaction
A reaction where both oxidation and reduction occur
