6 - Electrolysis

Question 1

What is electrolysis?

Answer 1

Using an electric current to break down ionic compounds (an electrolyte)

Question 2

How does electrolysis work?

Answer 2

1. Dip two electrodes into a melted/dissolved electrolyte solution
2. Connect the anode to the positive terminal and the cathode to the negative terminal of a power supply
3. Positive ions move to the cathode while negative ions move to the anode
4. Ions lose charge and become elements at the electrodes, gases & metals are deposited there

Question 3

What is the order of discharge at the anode?

Answer 3

1. Halides
2. Hydroxides
3. All others

Question 4

What is the order of discharge at the cathode?

Answer 4

The least reactive goes first

Question 5

What is aluminium used for?

Answer 5

• Aeroplanes
• Cans
• Overhead power cables
• Foil
• Bike frames & car bodies

Question 6

How do you separate aluminium from bauxite?

Answer 6

1. Melt aluminium oxide with molten cryolite to lower the melting point
2. Electrolyse at 850 C to produce molten aluminium & oxygen

Question 7

Zinc chloride (l) > ?

Answer 7

Zinc (s) + chlorine (g)

Question 8

Copper (II) bromide (aq) > ?

Answer 8

Copper (s) + bromine (aq)

Question 9

Lead bromide (l) > ?

Answer 9

Lead (s) + bromine (g)

Question 10

Aluminium oxide (l) > ?

Answer 10

Aluminium (l) + oxygen (g)

Question 11

Sodium chloride solution (aq) > ?

Answer 11

Hydrogen (g) + chlorine (g) + sodium hydroxide solution (aq)