(A1) Electrolysis Flashcards
What is electrolysis?
When a current is passed through a substance, causing the substance to decompose
What is electrolysis used for?
To break apart ionic compounds
What state does a substance have to been in for electrolysis?
A substance must be dissolved (aqueous) in solution or be a liquid (molten)
Why must the substance in electrolysis be dissolved?
So that the ions are free to move and can conduct
What is the positive electrode?
Anode
What is the negative electrode?
Cathode
What is a cation?
A positively charged ion that would be attracted to the cathode
What is an anion?
A negatively charged ion that would be attracted to the anode
What happens at the anode?
Negative ions lose electrons (they are oxidised)
What happens at the cathode?
Positive ions gain electrons (they are reduced)
Which cation will go to the cathode?
H+ (unless it is gold, copper or silver) because it is lower in the reactivity series
At the anode what happens if there is an halide(group 7) ion?
A halogen will form (Cl2 or Br2)
What happens at the anode if there is no halide?
Oxygen gas is formed
What is the equation for oxygen gas?
40H- –> O2 +H20 + 4e-
What is an electrolyte?
An ionic compound solution (a liquid that can conduct electricity)