C6: Electrolysis

The process of splitting ionic compounds into different elements they are made of. Electrolysis conducts electricity to work.

Electrodes Electrolyte Anode Cathode

When ionic compounds dissolve in water to make a solution that conducts electricity

When a voltage (direct current) is applied across the electrolyte, charged ions are attracted to the electrode with with the opposite charge to the ion

Anode Cathode Anions are negatively charged ions and are attracted to the positive electrode (anode) Cations are positively charged and are attracted to the negative electrode (cathode)

Electron transfer, production of elements

Reactive metals are extracted from molten ores. Electrolysis is used to extract metals like aluminium which are higher in the reactivity series than carbon

Oxygen is formed at the carbon anode. Carbon and oxygen react together to create carbon dioxide. Anode is usually made of carbon as it is a good conductor of electricity and is cheap. This is also where any non metal is formed

Aluminium is formed at the cathode. This is also where any metal is formed.

Lots of energy required to Produce electric current Melt the solid ionic compound to allow ion flow Very expensive

Products of electrolysis of aqueous solutions are unpredictable as water molecules split up to give hydrogen ions and hydroxide ions

Hydrogen is produced if the metal is higher than hydrogen in the reactivity series. The metal is produced if hydrogen is higher than the metal in the reactivity series

What is formed at the anode mainly depends if there are halide ions If halide ions are present, respective halogen forms If there are no halide ions, oxygen is formed

At the anode, this is where oxidation takes place (loss of electrons and gain of oxygen) Half equation for bromine 2Br- > Br2 + 2e-

At the cathode, this is where reduction takes place (gain of electrons and loss of oxygen) Half equation for magnesium Mg2+ + 2e- > Mg