Electrolysis Flashcards
What is the ore of aluminium called?
Bauxite (Al2O3)
What is Bauxite mixed with to form a mixture?
Cryolite
Why is Bauxite mixed with cryolite?
Ions are free to move in the mixture and cryolite lowers the melting point
What electrode will aluminium form at?
Negative because of positive ions that metals form
What will form at the positive electrode
Oxygen because of the negative ions that non-metals form
Why will the positive electrode need replacing?
Oxygen reacts with the carbon (electrode) which corrodes the electrode
Why is aluminium extracted from its ore using electrolysis?
Because it is more reactive than carbon
What will happen if the metal present is more reactive than hydrogen in an aqueous solution?
Hydrogen will form at the negative electrode
What will happen if the solution contains a halide ion in an aqueous solution?
The halogen gas will form at the positive electrode
What will happen if the solution contains no halide ions in an aqueous solution?
Oxygen is formed at the positive electrode
What ions do aqueous solutions contain?
H+ OH-
What is an ionic half equation?
A half-equation shows you what happens at one of the electrodes during electrolysis. Electrons are shown as e-. A half-equation is balanced by adding, or taking away, a number of electrons equal to the total number of charges on the ions in the equation.
OILRIG
- Oxidation is loss (of electrons)
- Reduction is gain (of electrons)
Example of reduction half equation
Pb2+(aq) + 2e- → Pb
Example of oxidation half equation
Mg(s) → Mg2+(aq) + 2e-
