RP8 - Measuring EMF of an electrochemical cell

Question 1

How do electrochemical cells produce a potential difference?

Answer 1

Via a redox reaction

Question 2

When is the potential difference between 2 half cells maximal?

Answer 2

When there is no current flowing

Question 3

What are the standard conditions for measuring electrochemical cells

Answer 3

298K
100 KPa
1.0moldm^3 solution

Question 4

What is the purpose of a salt bridge?

Answer 4

Allows ions to flow between solutions without the solutions mixing

Question 5

How is a salt bridge made?

Answer 5

Soaking filter paper in potassium nitrate solution

Question 6

Why is potassium nitrate used as a salt bridge?

Answer 6

Both ions are soluble and do not react to form precipitates with the ions

Question 7

How can you measure the comparative electrode potentials of different metals?

Answer 7

File a piece of copper and connect to positive voltmeter terminal
Saturate piece of filter paper in KNO3
Connect voltmeter to another piece of metal
Hold metal against filter paper and record voltmeter value