C10 Electrolysis Flashcards
Name 4 key things required for electrolysis
- Complete circuit (with cell)
- Anode (positive electrode)
- Cathode (negative electrode)
- electrolyte
Why must ionic compounds be molten to electrolyse
So ions are free to move and a charge can be carried
When you electrolyse a molten ionic substance what happens to both ions
Metal - Attracted to the cathode where they gain an electron to become a pure metal atom rather than an ion
Non-metal - Attracted to the anode where they loose an electron and become a pure non-metal atom rather than an ion
What would be the half equations of the electrolysis of this molten solution:
2NaCl(l) ——–> 2Na(s) + Cl2(g)
Cathode - 2Na+(l) + 2e- ———–> 2Na(s)
Anode - 2Cl-(l) ——-> Cl2(g) + 2e-
What are the electrodes made of
Graphite (carbon)
What is a use of electrolysis
Extracting reactive metals from ores containing the metals
Half equation for the ionisation of water
H2O(l) ———> H+(aq) + OH-(aq)
During electrolysis why is molten aluminium oxide mixed with cryolite
It lowers the melting point of the molten solution so it requires less energy to electrolyse
Name the 3 main acids and their formulas
Hydrochloric acid - HCl
Sulfuric acid - H2SO4
Nitric acid - HNO3
In electrolysis of solutions, when is the metal NOT produced at the cathode
When the metal is more reactive than hydrogen
In electrolysis of a solution what are the two possible substances that can be produced at the anode
- If the non-metal is a halogen then the halogen gas is formed at the anode
- If the non-metal isn’t a halogen then oxygen gas is released at the anode
In electrolysis of a solution what are the two possible substances that can be produced at the cathode
- If the metal is more reactive than hydrogen then hydrogen gas is released at the cathode
- If the metal ion is less reactive than hydrogen then the metal is released at the cathode as a solid
