Electrolysis of Aqueous Solutions

Question 1

what is an electrochemical cell?

Answer 1

a circuit, made up of the anode, the cathode, electrolyte, a power source and the wires that connect the two electrodes

Question 2

how to set up an electrochemical cell for an aqueous solution

Answer 2

1. get two inert electrodes
2. clean the surfaces of the electrodes using some emery paper
3. from this point on do not touch the surfaces of the electrodes with your hands so grease is not transffered back onto the strips
4. place both electrodes in a beaker filled with your electrolyte
5. connect the electrodes to a power supply using crocodile clips and wires - when you turn the power supply on, a current will flow through the cell

Question 3

what power supply is used for electrolysis?

Answer 3

a direct current (d.c.)

Question 4

what terminal of the power supply is the anode attached to?

Answer 4

the positive terminal

Question 5

what terminal of the power supply is the cathode attached to?

Answer 5

the negative terminal

Question 6

what other ions are involved in aqueous electrolysis?

Answer 6

the ions from water:
hydrogen ions (H+)
hydroxide ions (OH-)

Question 7

what happens at the cathode in aqueous electrolysis?

Answer 7

• if H+ ions and metal ions are present, hydrogen gas will be produced if the metal is MORE reactive than hydrogen
• if the metal is LESS reactive than hydrogen then a solid layer of the pure metal will be produced instead

Question 8

what happens at the anode in aqueous electrolysis?

Answer 8

• if OH- and halide ions are present, molecules of chlorine, bromine or iodine will be formed
• if no halide ions are present, then oxygen will be formed