Electrolysis and what happens at each electrode

What is electrolysis?

The breakdown of an ionic substance using electricity

What is an electrolyte?

A substance that conducts electricity through mobile ions when molten or dissolved

In an electrolytic cell, which electrode is connected to the negative terminal of the power supply?

The cathode

Which particles move towards the cathode during electrolysis?

Cations

What happens to ions at the cathode?

Positive ions gain electrons

Which process occurs at the anode during electrolysis?

Oxidation by losing electrons

Why must an ionic compound be molten or dissolved before it can be electrolysed?

Its ions must be free to move

During electrolysis of molten lead bromide, what forms at the cathode?

Lead

Which half-equation describes the formation of lead at the cathode from molten lead bromide?

Pb²⁺ + 2e⁻ → Pb

Which half-equation occurs at the anode during electrolysis of molten lead bromide?

2Br⁻ → Br₂ + 2e⁻

Aqueous copper sulfate is electrolysed using inert electrodes. What forms at the cathode?

Copper metal

Aqueous copper sulfate is electrolysed using inert electrodes. What forms at the anode?

Oxygen gas

Concentrated aqueous sodium chloride is electrolysed using inert electrodes. Which products form?

Hydrogen at the cathode and chlorine at the anode

During electrolysis of acidified water with inert electrodes, which gases are produced?

Hydrogen at the cathode and oxygen at the anode

What volume ratio of hydrogen to oxygen is produced by electrolysis of acidified water?

2:1

Aqueous copper sulfate is electrolysed using copper electrodes. What happens to the electrode masses?

The cathode gains mass and the anode loses mass

Which half-equation occurs at a copper anode during electrolysis of copper sulfate using copper electrodes?

Cu → Cu²⁺ + 2e⁻

What is the purpose of an inert electrode in electrolysis?

To carry current without taking part in the overall chemical reaction