Chemistry - Electrolysis

Question 1

What is electrolysis?

Answer 1

The process of passing an electric current through a compound to chemically separate its components

Question 2

What is an electrolytic cell?

Answer 2

A device that converts electrical energy into chemical energy

Question 3

What are the parts of an electrolytic cell?

Answer 3

• Battery (power supply)
• Connecting wire (connected to the solution through electrodes)
• Electrodes
• Electrolyte

Question 4

What are the characteristics of electrodes?

Answer 4

• Made from graphite or platinum (good conductors of electricity, unreactive - INERT - to avoid contamination)
• Anode: the electrode connected to the positive terminal, attracts anions
• Cathode: the electrode connected to the negative terminal, attracts cations

Question 5

What are the characteristics of the electrolyte?

Answer 5

• Molten (or liquid) ionic salt (solution that is an electrical conductor)
• Within the electrolyte, flow of electrons = flow of electric current
• They are molten binary ionic compounds (salt containing a cation and anion in liquid state)

Question 6

What are the adv and disadv of graphite and platinum as electrodes?

Answer 6

Graphite:
Adv - High melting point, will not melt when used in electrolysis of molten binary ionic compounds.
Disadv - Will react with oxygen gas under high temperatures to produce carbon dioxide. Graphite anodes may need to be periodically replaced (carbon dioxide slowly burns away the anode).

Platinum:
Adv - Does not take part in the electrolysis reaction.
Disadv - Lower melting point than graphite. Might melt when used in electrolysis of molten binary ionic compounds. Mainly used in the electrolysis of aqueous electrolytes.

Question 7

What is the process of electrolysis?

Answer 7

In electrolysis, electrons flow from the negative terminal to the positive terminal of the power supply.
The flow of electrons is from the anode to the cathode THROUGH THE CIRCUIT
Negatively charged atoms (anions) move toward the anode and lose electrons → oxidised
Positively charged atoms (cations) move toward the cathode and gain electrons → reduced
Therefore, the compound is separated into its components.