How a current splits an ionic compound, what forms at each electrode when it is molten, and the rules for which products form from a solution.
What you will learn
- Explain why an ionic compound must be molten or dissolved to be electrolysed
- Name the products at each electrode for a molten compound
- Predict the products from an aqueous solution
- Say what is left in the solution afterwards
What electrolysis does
An ionic compound conducts electricity only when it is molten or dissolved: then its ions are free to move.
This liquid is the electrolyte.
- Positive ions move to the cathode (negative electrode) and gain electrons.
- Negative ions move to the anode (positive electrode) and lose electrons.
- The electrodes are usually inert (graphite or platinum), so they do not react.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- What electrolysis does
- Molten compounds
- Aqueous solutions
9 practice questions, marked as you go; about 20 minutes in all.
Key terms
Electrolyte, Cathode, Anode, Inert, Metal at the cathode, Non-metal at the anode
In this unit: Chemical changes: reactivity, acids and electrolysis
The reactivity series and metal extraction, oxidation and reduction, acids, salts and pH, titrations, and electrolysis of melts and solutions.