Core Practical 10

Question 1

Describe a method for setting up Electrochemical cell

Answer 1

For each half cell clean the strips of metal with sandpaper so there is surface area exposed for the reactions to occur. Soak filter paper with KNO3 to create a salt bridge. Use high resistance voltmeter to find Ecell

Question 2

What does a salt bridge do?

Answer 2

Completes the circuit by allowing the movement of ions . K+ and NO3- minimises the chance of precipitates forming

Question 3

What is an electrochemical cell?

Answer 3

two half-cells connected by salt bridge with their electrodes connected to a voltmeter allowing flow of electrons. electrical energy generated by chemical redox reactions

Question 4

What does a half cell consist of?

Answer 4

Chemical species present in a redox half-equation.

metal electrode in metal ion solution

Question 5

Why may a graphite or platinum half cell be used?

Answer 5

very unreactive. won’t affect voltmeter readings

Question 6

How do you measure comparative electrode potentials of different metals?

Answer 6

Measure EMF with voltmeter connected between electrodes, repeat with different combinations of metals.

Question 7

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

Answer 7

To remove the oxide layer on the outside of the metal.