Electrolysis

Question 1

What is electrolysis?

Answer 1

The splitting up of an ionic substance by passing an electric current through it.

Question 2

What happens if you pass an electric current through an ionic substance that’s molten or in solution?

Answer 2

It breaks down into elements.

Question 3

What is the electrolyte?

Answer 3

Liquid to conduct the electricity, usually the molten or dissolved ionic substance.

Question 4

What does the electrolyte contain?

Answer 4

Free ions.

Question 5

What conducts the electricity?

Answer 5

Free ions.

Question 6

What happens at the negative electrode?

Answer 6

Reduction.

Question 7

What happens at the positive electrode?

Answer 7

Oxidation.

Question 8

What is reduction?

Answer 8

Gain of electrons.

Question 9

What is oxidation?

Answer 9

Loss of electrons.

Question 10

In the electrolysis of lead bromide, what is produced at the positive electrode?

Answer 10

Bromine.

Question 11

In the electrolysis of lead bromide, what is produced at the negative electrode?

Answer 11

Lead.

Question 12

What happens if there are more than two free ions in the electrolyte at the negative electrode?

Answer 12

Hydrogen will be produced unless the metal is less reactive than it.

Question 13

What happens if there are more than two free ions in the electrolyte at the positive electrode?

Answer 13

If no halide is present, oxygen will be formed.

Question 14

What does the electrolysis of sodium chloride solution produce?

Answer 14

Hydrogen, chlorine and sodium hydroxide.

Question 15

In the electrolysis of sodium chloride, what is produced at the negative electrode?

Answer 15

Hydrogen.

Question 16

In the electrolysis of sodium chloride, what is produced at the positive electrode?

Answer 16

Chlorine.

Question 17

In the electrolysis of sodium chloride, what is left in the solution?

Answer 17

Sodium hydroxide.

Question 18

In the electrolysis of sodium chloride, what is the half equation for the negative electrode?

Answer 18

2H+ + 2e- –> H2

Question 19

What is chlorine used for?

Answer 19

Bleach and plastics.

Question 20

What is sodium hydroxide used for?

Answer 20

Chemical industry and soap.

Question 21

What is the main ore of aluminium?

Answer 21

Bauxite.

Question 22

What is cryolite used for?

Answer 22

To bring the high melting point down.

Question 23

What are the electrodes made of?

Answer 23

Carbon (graphite)

Question 24

In the extraction of aluminium, what forms at the positive electrode?

Answer 24

Oxygen.

Question 25

In the extraction of aluminium, what forms at the negative electrode?

Answer 25

Aluminium.

Question 26

In the extraction of aluminium, why do the positive electrodes have to be replaced?

Answer 26

Carbon dioxide is produced when the oxygen reacts with the carbon.

Question 27

In electroplating, what is the negative electrode?

Answer 27

Object to be plated.

Question 28

In electroplating, what is the positive electrode?

Answer 28

Pure metal to plate with.

Question 29

In electroplating, what does the electrolyte contain?

Answer 29

Ions of the plating metal.

Question 30

What can electroplating be used for?

Answer 30

1. Decoration

2. Conduction

Question 31

In the electrolysis of sodium chloride, what is the half equation for the positive electrode?

Answer 31

2Cl- - 2e- –> Cl2