electrolysis

Question 1

What is electrolysis?

Answer 1

Splitting an ionic substance using electricity

Question 2

What type of compound can be broken down by electrolysis?

Answer 2

Ionic compounds.

Question 3

Why must the compound be molten or dissolved in water?

Answer 3

So the ions are free to move and carry current.

Question 4

What is the electrolyte?

Answer 4

The liquid containing free-moving ions.

Question 5

What charge is the cathode?

Answer 5

Negative (-)

Question 6

What charge is the anode?

Answer 6

Positive (+)

Question 7

What type of ion goes to the cathode?

Answer 7

Positive ions (cations)

Question 8

What type of ion goes to the anode?

Answer 8

Negative ions (anions)

Question 9

What happens to ions at the cathode?

Answer 9

They gain electrons (reduction).

Question 10

What happens to ions at the anode?

Answer 10

They lose electrons (oxidation).

Question 11

What does OIL RIG stand for?

Answer 11

Oxidation Is Loss, Reduction Is Gain (of electrons)

Question 12

In aqueous solutions, what is produced at the cathode if the metal is more reactive than hydrogen?

Answer 12

Hydrogen gas.

Question 13

In aqueous solutions, what is produced at the anode if there is a halide ion?

Answer 13

A halogen (Cl₂, Br₂, I₂)

Question 14

What is produced at the anode if there is no halide ion present?

Answer 14

Oxygen gas.

Question 15

What is produced when molten lead bromide is electrolysed?

Answer 15

Lead at the cathode, bromine at the anode.

Question 16

Which process happens at the cathode?

Answer 16

Reduction (gain of electrons)

Question 17

Which process happens at the anode?

Answer 17

Oxidation (loss of electrons)

Question 18

where do positive ions go?

Answer 18

Positive ions go to the negative electrode (called the cathode).

Question 19

where do negative ions go?

Answer 19

Negative ions go to the positive electrode (called the anode).

Question 20

What happens to an ionic compound when it is melted or dissolved in water?

Answer 20

The ions become free to move and can carry electric current, so the liquid or solution conducts electricity.

Question 21

Explain why electrolysis is used to extract aluminium from aluminium oxide.

Answer 21

Aluminium is very reactive and cannot be extracted by heating with carbon.

Electrolysis breaks down molten aluminium oxide into aluminium metal and oxygen.

The process requires a lot of energy to melt the compound and pass electric current.

Question 22

Why is cryolite mixed with aluminium oxide in the electrolysis process?

Answer 22

Cryolite lowers the melting point of aluminium oxide, reducing energy costs and making electrolysis easier.

Question 23

Write the half-equation for the reaction at the cathode during aluminium extraction.

Answer 23

Al³⁺ + 3e⁻ → Al

Question 24

Write the half-equation for the reaction at the anode during aluminium extraction.

Answer 24

2O²⁻ → O₂ + 4e⁻

Question 25

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

Answer 25

Oxygen gas reacts with the carbon anode, forming carbon dioxide and causing the anode to wear away.

Question 26

Predict the products when molten lead bromide is electrolysed using inert electrodes.

Answer 26

Lead metal is produced at the cathode. Bromine gas is produced at the anode.

Question 27

What is produced at the cathode if the metal is less reactive than hydrogen?

Answer 27

The metal itself is produced.

Question 28

What gas is produced at the anode during electrolysis of an aqueous solution containing halide ions?

Answer 28

The halogen gas (e.g., chlorine, bromine, iodine) is produced.

Question 29

What gas is produced at the anode if no halide ions are present?

Answer 29

Oxygen gas is produced.

Question 30

Why does water affect the products formed during electrolysis of aqueous solutions?

Answer 30

Water breaks down into hydrogen ions (H⁺) and hydroxide ions (OH⁻), which can be discharged instead of the ions from the dissolved compound.