CC10 - Electrolytic Processes Flashcards
What is an electrolyte
A molten or dissolved ionic compound
What is electrolysis
When a substance is broken down using electricity
What is the positive electrode called
The anode
What is the negative electrode called
The cathode
Where do the ions move in electrolysis
- positive ions (cations) move towards the cathode
- negative ions (anions) move towards the anode
ELECTROSTATIC ATTRACTION
What happens to the anions and cations at their respective electrodes
- cations = reduced, gain electrons
- anions = oxidised, lose electrons
What happens when the ions become uncharged substances by gaining/ losing electrons
The are discharged from the electrolyte
Why can’t ionic solids be electrolysed
The ions are in fixed positions, and cannot move
Why can molten/ dissolved ionic compounds be electrolysed
The ions are free to move and conduct electricity
What happens to positive metal ions in electrolysis
They are reduced to metal atoms at the cathode
What happens to negative ions in electrolysis
They’re oxidised to atoms/ molecules at the anode
Why is electrolysis of aqueous solutions more complicated
There are H+ ions and OH- ions from the water as well as the ions from the ionic compund
What occurs at the cathode during the electrolysis of aqueous solutions if H+ and metal ions are present
- if the metal is more reactive than hydrogen, hydrogen produces at the cathode
- if the metal is less reactive than hydrogen, a solid layer of pure metal is produced at the cathode
What happens at the anode during the electrolysis of aqueous solutions
- if halide ions are present (halogens), the molecules of the halogen form at the anode
- if no halide ions are present, oxygen is formed at the anode
What happens at each electrode in the electrolysis of copper sulfate solution, if inert electrodes are used
- cathode: copper metal (copper is less reactive than hydrogen)
- anode: oxygen (no halide ions present)
