Paper 3: Required practical 8 - Measuring EMF of an electrochemical cell

Question 1

How do you measure comparative electrode potentials of different metals?

Answer 1

• File a piece of copper using emery paper and connect to the positive voltmeter terminal
• Cut a piece of filter paper, saturate with KNO3 solution and place on top of the copper
• Connect the voltmeter to another piece of metal
• Hold the metal agaisnt the filter paper and record the voltmeter value
• Repeat with different metals and record the results in a table

Question 2

Why do you need to file/sand away the outer layer of the metal?

Answer 2

It removes the oxide layer on the outside if the metal