Required practical 8

Question 1

What is the aim of the experiment

Answer 1

To set up a zinc-copper electrochemical cell

Question 2

Step 1

Answer 2

Clean a piece of copper and a piece of zinc using emery paper or fine grade sandpaper

Question 3

What does the emery paper/ fine grade sandpaper do?

Answer 3

Removes the oxide layer on the metals

Question 4

Step 2

Answer 4

Degrease the metals using propanone

Question 5

What is the problem with having grease

Answer 5

May stop the electrochemical cell from functioning properly - alters EMF reading

Question 6

Step 3

Answer 6

Add the copper into a 100cm3 beaker with 50cm3 of 1.0 moldm-3 copper sulfate solution

Question 7

Step 4

Answer 7

Add the zinc into a 100cm3 beaker with 50cm3 of 1.0 moldm-3 zinc sulfate solution

Question 8

Step 5

Answer 8

Lightly plug one end of a plastic u-tube with cotton wool, fill it with 2.0moldm-3 NaCl solution and then plug the other end

Question 9

Step 6

Answer 9

Join the two beakers with the plastic u-tube so that each end is fully submerged in the solutions in each beaker

Question 10

What is the role of u-tube

Answer 10

Acts as a salt bridge

Question 11

Step 7

Answer 11

Connect the two half cells by connecting the two metals using crocodile clips and lead, including a voltmeter in the circuit

Question 12

What is the purpose of the voltmeter

Answer 12

To read the EMF of the cell

Question 13

What is the role of a salt bridge

Answer 13

1. Allows the movement of ions to balance out the charges
2. Must not react with the electrolyte or the ions in solution
3. KNO3 is often used