What is electrolysis
Using electricity to break down a substance
What happens to an Ionic substance when it is melted or dissolved in water
Ions become free to move around
Why can electrolysis not be used on solids
They cannot conduct electricity
Positive electrode
Anode
Negative electrode
Cathode
Positive ions go to the
Cathode
Negative ions go to the
Anode
For which metals is electrolysis needed
Ones more reactive than carbon
Disadvantages of electrolysis
Need large amounts of energy
Why is aluminium oxide mixed with cryolite
To lower the melting point
What is produced at the anode and cathode in the electrolysis of alumina oxide
Aluminium and oxygen
Why does the anode need to be replaced
Wears away
What is produced at the cathode in the electrolysis of solutions
Hydrogen if it is less reactive
In the electrolysis of sodium chloride what are the products
Chlorine gas
Hydrogen
Why is sodium not produced
More reactive than hydrogen
What is produced at the anode
Halogen or oxygen
Half equation for the discharge of hydrogen ions
2H+ (aq)+2e- —> H2(g)
Test for chlorine gas
Bleaches blue litmus paper white
What does bubbling at the cathode indicate
Production of hydrogen gas
What is observed at the cathode
Brown/ red coating
Half equation for hydroxide
4OH-(aq)—>O2(g) + 2H2O(l)+4e-
Products for molten iron bromide
Iron and bromine
Products for molten zinc oxide
Zinc and oxygen
Products for molten sodium chloride
Sodium
Chlorine
