C3.4 - Electrolysis Flashcards
What is electrolysis?
A process in which an electric current is passed through a compound, causing a chemical change
What are the three components of electrolysis?
An electrolyte
Two electrodes
A power supply
What is an electrolyte?
A compound in a molten or aqueous state, which contains mobile ions and can conduct electricity
What material should the two electrodes be made from?
Metal or graphite, as they can conduct
What is the negative electrode?
Cathode
What is the positive electrode?
Anode
What happens to the ions ion electrolysis?
The more reactive cations are reduced at the cathode to become atoms
The more reactive anions are oxidised at the anode to become atoms
What happens during electrolysis with molten compounds?
The positive ions go to the cathode and the negative ions go to the anode and become atoms
What are the rules for electrolysis of aqueous solutions?
Hydrogen is produced at the cathode unless a more reactive metal is present.
Less reactive metals are copper, silver, gold and platinum
Oxygen is produced at the anode unless a halide ion is present
What is electroplating?
A type of electrolysis with non-inert electrodes, where the:
Cathode is the object you want to coat
Anode is the metal you want to coat with
The electrolyte is a solution containing ions of the coating metal
How does electroplating work?
Metal ions from the electrolyte are discharged on the surface of the object (cathode).
These ions are replaced by metal ions leaving the surface of the anode
