4.4.3 Electrolysis

Question 1

What is electrolysis?

Answer 1

It is a chemical change that breaks down an ionic compound using electricity.

Question 2

What is an electrolyte?

Answer 2

It is the molten compound which consists of ions

Question 3

What are electrodes?

Answer 3

They are conducting rods made out of inert substances (usually carbon in the form of graphite).

Question 4

What are the two electrodes used in electrolysis called, and what charge do they have?

Answer 4

An anode has a positive charge
A cathode has a negative charge.

PANIC: Positive Anode Negative Is Cathode

Question 5

What connects the two electrodes together (powers them)?

Answer 5

A cell.

Question 6

For the compound “Sodium Chloride”, which ion will be attracted to which electrode?

Answer 6

Sodium + will be attracted to the cathode -
Chloride - will be attracted to the anode +

Question 7

For the compound “Lead Bromide”, which ion will be attracted to which electrode?

Answer 7

2 Bromine - will be attracted to the anode +
Lead 2+ will be attracted to the cathode -

Question 8

What are the ions attracted to the cathode and anode called?

Answer 8

The ions attracted to the cathode are called cations.
The ions attracted to the anode are called anions.

Question 9

For the electrolysis of aqueous solutions, when is hydrogen produced?

Answer 9

If the metal is above hydrogen in the reactivity series and is attracted to the cathode.

Question 10

For the electrolysis of aqueous solutions, when is oxygen produced?

Answer 10

If the metal is above oxygen in the reactivity series and is attracted to the anode.

Question 11

How can reactions at electrodes can be represented?

Answer 11

They can be represented by half equations, for example:

2H+ + 2e- → H2

and

4OH- → O2 + 2H2 O + 4e-