1. The following slides should help you with your revision, but should not be your only form of revision.
Remember to use your notes, a textbook, websites and Past Papers to help you. You can also ask a chemistry teacher for help too.

2. Mains electricity Batteries ( More accurately …cells)
To make many household appliances work a supply of electricity is needed, name the two forms the supply normally comes in?
Mains electricity
Batteries ( More accurately …cells)

3. What happens in an electrical wire when electricity is passed along?
There is a flow of electrons along the wire.

4. What is the definition of current?
Current is a flow of electrons.

5. Why do batteries (cells) need replaced?
The chemical reaction is complete or one of the reactants are used up, the reaction stops so no more electricity is produced.

6. What energy change takes place in a cell (battery)?
Chemical energy is changed into electrical energy.

7. Some batteries are rechargeable, name two examples of rechargeable batteries?
Lead-acid
Nickel-cadmium

8. Give some advantages of Batteries over Mains Supply?
They can be easily transported.
Can be used almost anywhere.
Less dangerous.

9. Give some disadvantages of Batteries over Mains Supply?
They don’t last as long.
More expensive.
Uses up metals… finite resources.

10. How can a cell be made to produce electricity?
Electricity can be produced by connecting different metals together with an electrolyte to form a cell.

11. Label the parts of the Electrochemical CellsD
External Circuit
…electrons flow. A
Metal A
Metal B B E
Internal Circuit
…ions move. C
Electrolyte

12. How can the voltage in electrochemical cell be made as large as possible?
The further apart the metals are from each other in the Electrochemical Series ( Check the Data Book!!) the greater the voltage produced.

13. Which pair of metals would give the largest volume?
Mercury and silver
Aluminium and magnesium
Zinc and iron
Lead and Calcium

14. What is the purpose of the electrolyte in an electrochemical cell?
The purpose of the electrolyte in the cell is to complete the circuit by allowing ions to carry the charge in the internal circuit.

15. What is the definition of an electrolyte?
An electrolyte is a solution or paste which allows electricity to move through it.

16. What types of solutions make good electrolytes?
Ionic solutions.
Eg salt

17. Why do ionic solutions make good electrolytes?
Ionic solutions make good electrolytes because the ions are free to move.

18. Which direction do electrons flow in an electrochemical cell?
Electrons always flow from the metal higher to the metal lower in the Electrochemical Series, via the external circuit.

19. What is the definition of a displacement reaction?
A more reactive metal will displace a less reactive metal from a solution of its ions.

20. Complete the Results for these Displacement Reactions:
Solution
Metal
Sodium
sulphate
Zinc sulphate
Copper sulphate
Silver nitrate Mg no
Yes Sn Cu
Conclusion:
A more reactive metal displaces a less reactive metal from a solution of its ions.

21. Zinc is added to copper (II) sulphate solution, what happens?Zn
Zn Zn
Cu2+ SO Zn2+ SO42-
SO42- Cu SO Zn2+
Cu2+ SO Cu SO42- Cu
Brown solid (Cu ) appears. Zn atoms go into solution,
blue colour becomes paler.

22. Displacement Theory Step 3 Write the ion –electron equation for each.
Cu 2+(aq Cu(s)
Zn (s) Zn2+(aq)
+ 2e
Reduction
+ 2e
Oxidation

23. How could you confirm the position of hydrogen in the electrochemical series using displacement reactions?
If lead is added to an acid then hydrogen will be produced showing lead is higher than hydrogen in the electrochemical series.
However, if copper is added to acid no hydrogen will be produced as copper is less reactive than hydrogen so can not displace the hydrogen ions from the acid.
This would show that hydrogen is between lead and copper in the electrochemical series.