Electrolysis Flashcards
(21 cards)
What is electrolysis
Electrolysis is defined as the conduction of electricity by an electrolyte, leading to the decomposition of the electrolyte
Cathode is connected to the ____ terminal
Negative
Anode is connected to the ____ terminal
Positive
What is an electrolyte
An electrolyte is defined as a molten or aqueous ionic compound which is decomposed through the process of electrolysis
Structure of electrolyte (ionic compounds)
A lattice of positive and negative ions, held together by strong electrostatic forces of attraction between oppositely charged ions
Why is it important for electrolyte to be molten/aqueous and not solid
In solid, ions are held in fixed positions and hence unable to move and carry a current. In aqueous/molten, ions are free to move and carry a charge
Disadvantage of platinum electrode
Expensive
Disadvantage of graphite electrode
May react with oxygen to form CO2
How does conduction of electricity in electrolyte differ from electrode
Electrolytes conduct electricity through mobile ions while electrodes conduct electricity through see of delocalised electrons
What ions does cathode attract
Cations
What ions does anode attract
Anions
Which redox takes place at cathode
Reduction
Which redox takes place at anode
Oxidation
Why need maintain heat source in molten ionic compounds
Electrolytes are ionic compounds, solid at room temperature hence unable to conduct electricity. Heat source maintains the electrolytes in molten state so ions can move and carry charge
Recap metal reactivity series
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Mercury
Silver
Gold
Platinum
Observations using inert electrodes
- Cathode increases in size with coating
- Bubbles of gas produced at anode
- Solution decolourises
Observations using non inert electrodes
- Cathode increases in size with coating
- Anode decreases in size
Applications of electrolysis
- Purification of copper
- Electroplating
Electroplating cathode
Metal to be electroplated
Why cannot plate with more reactive metals
More reactive metals (above hydrogen), hydrogen would be selectively discharged instead
Why can electroplating only be used for metallic objects
Only metals can conduct electricity at room temperature. Hence only metallic objects can be used as a cathode to allow cations to discharge upon it.
