1. Electrolysis

2. What is electrolysis? Electrolysis means “breaking up a compound with electricity” From the Greek Electro – electricity Lysis – breaking up Electrolysis keywords Anode – positive electrode Cathode – negative electrode Ion- charged particle Electrolyte – substance that can be electrolysed Anion – ion that goes to the anode Cation – ion that goes to the cathode

3. What is electrolysis? Electrolysis only works on substances made of ions. These are mostly the compounds of metals. The products of electrolysis are vital for our industry.

4. What is electrolysis? Electrolysis will only work if the ions in the substances are free to move. In solids the ions are fixed in place, so electrolysis will not work on solids But Electrolysis works on liquids and molten compounds Electrolysis works on solutions.

5. Melting When ionic crystals melt the ions are free to move

6. Dissolving When an ionic substance dissolves the ions spread out and are free to move

7. 1 Electrodes Negative Cathode Positive Anode D.C. current Sodium Chloride Solution + - A little revision Name the following 2 3 4 5

8. When Salt Dissolves The sodium ions and the chloride ions split up. This gives us Na + ions and Cl - ions Some water molecules also split up This gives us H + ions and OH - ions

9. Negative Cathode Positive Anode D.C. current + - Na+ Cl- H+ OH- Where will the ions go?

10. Negative Cathode Positive Anode D.C. current + - Na+ Cl- H+ OH- At the anode Cl 2 There are lots of chloride ions in brine. They are attracted to the anode first The chloride ions lose electrons and become chlorine gas 2Cl -  Cl 2 + 2e - OXIDATION The hydroxide ions get left behind in solution. There aren’t enough to discharge. 2e -

11. Negative Cathode Positive Anode D.C. current + - Na+ Cl- H+ OH- At the cathode 2e - The electrons get pumped into the cathode. Positive ions are attracted to it. Hydrogen ions get to the cathode before the sodium ions. Hydrogen gas is discharged. 2H + + 2e -  H2 Reduction Sodium ions are left behind in solution. H2H2

12. Negative Cathode Positive Anode D.C. current + - Na+ Cl- H+ OH- Where will the ions go? H2H2 Cl 2 2e -

13. Products The three main products are: Hydrogen gas Chlorine gas Sodium hydroxide solution Cl 2 H2H2 Na+OH-

14. Negative Cathode Positive Anode D.C. current + - Na+ Cl- H+ OH- In the Diaphragm Cell H2H2 Cl 2 2e - Cl- Cl 2