C2.7 - Electrolysis Flashcards
What happens when an ionic substance is melted or dissolved in water?
The ions are free to move around in the liquid or solution.
What happens when you pass an electric current through a molten ionic substance, such as lead bromide?
They break down into elements.
What is the process called when a molten ionic substance is broken down using a current?
Electrolysis?
During electrolysis, what are positive and negative ions drawn to?
Positive ions: The negative electrode (cathode)
Negative ions: The positive electrode (anode)
What happens if there is a mixture of ions?
The products formed depend of the reactivity of the elements involved.
What can reactions at electrodes be represented by?
Half equations.
How is aluminium manufactured?
By the electrolysis of a molten mixture of aluminium oxide and cryolite.
What is cryolite?
An aluminium compound which lowers the melting point, therefore making the process cheaper.
What happens at the electrodes when aluminium is manufactured?
Aluminium forms at the negative electrode and oxygen at the positive electrode. The positive electrode is made of carbon, which reacts with the oxygen to produce carbon dioxide.
What are the products when sodium chloride solution is electrolysed?
It produces hydrogen, chlorine and sodium hydroxide solution.
How are the products of electrolysed sodium chloride used?
Sodium hydroxide: the production of soap
Chlorine: the production of bleach and plastics.
