Chapter 6 - Electrolysis

Question 1

What is electrolysis?

Answer 1

The breakdown of a substance using electricity.

Question 2

What is the substance broken down by electrolysis called?

Answer 2

The electrolyte.

Question 3

State the scientific name for the positive and negative electrode.

Answer 3

P - anode
N - cathode

Question 4

Why can ionic compounds only be electrolysed when it is in a molten/liquid state?

Answer 4

The compounds ions can freely move and carry charge to electrodes.

Question 5

State which ion travels to which electrode.

Answer 5

Positive ions - Cathode (N)
Negative ions - Anode (P)

Question 6

What happens to the ions at the anode?

Answer 6

They are reduced (gained electrons).

Question 6

What happens to the ions at the anode?

Answer 6

They are reduced (gained electrons).

Question 6

What happens to the ions at the anode?

Answer 6

They are reduced (gained electrons).

Question 7

What is formed at each electrode during the electrolysis of copper chloride solution?

Answer 7

Cathode - Copper
Anode - Chlorine

Question 8

State the half equations for the electrolysis of aluminium oxide at each electrode.

Aluminium - Al2O3
Oxygen - O2

Answer 8

Cathode - Al3+ + 3e- = Al

Anode - 2O2- = O2 + 4e-

Question 9

Which ions are reduced and oxidised during the electrolysis of aluminium oxide?

Answer 9

Aluminium ions are reduced.
Oxygen ions are oxidised.

Question 10

What is aluminium oxide mixed with before electrolysis?

Answer 10

Molten cryolite.

Question 11

Why are positively charged ions attracted to the cathode?

Answer 11

The cathode is negatively charged, so positive charges will attract.

Question 12

Define electrode.

Answer 12

A rod conducting electricity. 1 positive and 1 negative.

Question 13

What happens to ionic compounds in electrolysis?

Answer 13

They are turned into elements via electrolysis

Question 14

What happens to ionic compounds in electrolysis?

Answer 14

They turn into elements via electrolysis

Question 15

State the three products produced when a student electrolyses sodium chloride solution.

Answer 15

• Chlorine gas (anode)
• Hydrogen gas (cathode)
• Sodium hydroxide

Question 16

How is chlorine attracted to the anode?

Answer 16

Negative chlorine ions (Cl-) are formed and attracted towards the anode, as opposites attract.

Question 17

A student is trying to perform an electrolysis of copper (II) chloride solution.
Describe an effective experiment to perform this electrolysis [6].

Answer 17

Measure 50cm3 of copper chloride solution into a beaker. [1]
Place lid with carbon rods over beaker [1]
Attach leads to rods and connect with a power supply [1]
Set pack at 4V for 5 minutes [1]
Use litmus paper to test for chlorine. If paper is bleach, chlorine is present. [1]
After 5 minutes, turn off power supply and check electrode surface for copper coatings, which are coppery-red [1]

Question 18

What happens to ions at the cathode?

Answer 18

They are oxidised (loses electrons)