Electrolysis AQA Chemistry Paper 1

Why do ionic compounds have to be molten or dissolved in liquid for electrolysis to occur?

The forces of attraction are broken so the ions are free to move

Name the charged particles that carry the current through a solution during electrolysis.

ions

What are the electrodes made from?

graphite (carbon)

How do we extract a metal that is more reactive than carbon?

Electrolysis

How do we extract metals that are less reactive than carbon?

Reduction with carbon

Why is aluminium oxide mixed with cryolite when extracting aluminium?

lower melting point

Why do we lower the melting point of aluminium oxide in electrolysis?

Reduce the amount of energy needed and to save money

Why must the anode be replaced regularly in the electrolysis of aluminium oxide?

The oxygen molecules produced at the anode react with the graphite (carbon), forming carbon dioxide gas.

Why is electrolysis expensive?

• melting the compounds such as aluminium oxide requires a great deal of energy

• a lot of energy is required to produce the electric current

How is water used in aqueous electrolysis?

Water partially ionises to produce some H⁺ and OH⁻ ions in aqueous solutions.

These ions participate in electrolysis alongside the ions from the dissolved compound.

This partial ionisation allows electrolysis to happen.

Why might hydrogen be produced at the cathode in aqueous electrolysis?

If the metal is more reactive than hydrogen

What happens if the aqueous solution contains halide ions in aqueous electrolysis

The halogen will be produced at the anode

What is a halide ion

a negative ion formed when a halogen atom gains an electron

In electrolysis what charge do metals have in electrolysis?

Positive

Which electrode do metals go to?

Cathode (negative)

In electrolysis what charge do non metals have

Negative

What electrode do non metals go to?

Anode (positive)

At which electrode does oxidation occur?

anode