Electrolysis

Electrolysis

1. Positively charged ions go to the negative electrode (cathode)

   • At the negative electrode, positively charged ions gain electrons (reduction)

2. Negatively charged ions go to the positive electrode (anode)

   • At the positive electrode, negatively charged ions lose electrons (oxidation)

3. Electrons move through the circuit from the anode, through the power supply and then through the cathode

4. Electrolysis is used to electroplate objects. This may be for a variety of reasons and includes copper and silver plating.

5. If there is a mixture of ions, the products formed depend on the reactivity of the elements involved

6. Ions that are more reactive than hydrogen produce hydrogen gas at the cathode (negative electrode)

7. Ions that are less reactive than hydrogen produce the metal of the element at the cathode (negative electrode)

8. Aluminium is maufactured by the electolysis of a molten mixture of aluminium oxide and cryolite.

   • 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.

9. The electrolysis of sodium chloride solution produces hydrogen and chlorine. Sodium hydroxide solution is also produced.

   • There are important reagents for the chemical industry eg sodium for the production of soap and chlorine for the production of bleach and plastics