RP8- Emf Of Electrochremical Cells

Question 1

What electrochemical cell is used in this experiment?

Answer 1

A copper- zinc cell

Question 2

Describe a method to measure the emf of an electrochemical cell

Answer 2

Clean a copper and zinc strip of metal with sandpaper, then degrease it with cotton wool and propanone

Create both the half cells. Place the copper strip in a 100cm3 beaker with 50cm3 of 1moldm3 CuSO4 solution.
Place the zinc strip in a 100cm3 beaker with 50cm3 of 1moldm of ZnSO4 solution

Create the salt bridge by soaking filter paper in a solution of NaCl. Place it across both beakers, so each end is emersed in solution

Connect the metal pieces to a wire with crocodile clips, including a voltmeter in the circuit. Read the voltmeter- is it is negative swap the positive and negative ends. The voltage is the emf

Question 3

What is the salt bridge used for in an electrochemical cell? What are the requirements for it?

Answer 3

To allow the movement of ion across the electrodes
It must be inert so it doesn’t react withy the electrolytes. It must conduct electricity

Question 4

Why are the pieces of metal degreased before the experiment?

Answer 4

Because the grease may prevent the electrochemical cell from working as efficiently

Question 5

Why is sandpaper used to clean the metal pieces?

Answer 5

To remove any oxide layers on the outside of the metal