Electrolysis

Question 0

Why do solid ionic compounds do not conduct electricity but molten or dissolved ionic compounds do?

Answer 0

Ions cannot move in solid.

Ions can move when molten or dissolved.

Question 1

What is an electrolyte?

Answer 1

A molten or dissolved ionic compound that decomposes when it conducts electricity.

Question 2

Define oxidation and reduction

Answer 2

OIL RIG
Oxidation is the loss of electrons
Reduction is the gain of electrons

Question 3

What is formed at the anode and cathode when a molten ionic compound conducts electricity?

Answer 3

Anode- non metal forms

Cathode- metal forms

Question 4

What are the possible products at the anode and cathode when a solution conducts electricity?

Answer 4

Anode- halogen or oxygen ( from the water )

Cathode- metal or hydrogen (from the water)

Question 5

Which ions are attracted to the positive electrode(anode)?

Answer 5

Negative ions

Question 6

Which ions are attracted to the negative electrode(cathode)?

Answer 6

Positive ions

Question 7

What is brine?

Answer 7

Concentrated sodium chloride solution.

Question 8

What is formed at the cathode when brine undergoes electrolysis?

Answer 8

Hydrogen

Question 9

What is formed at the anode when brine undergoes electrolysis?

Answer 9

Chlorine

Question 10

What is left in solution when brine undergoes electrolysis?

Answer 10

Sodium hydroxide solution

Question 11

Give a use of chlorine

Answer 11

Killing bacteria in drinking water, swimming pools , or making bleach

Question 12

Give a use or hydrogen

Answer 12

Making margarine or as a rocket fuel

Question 13

Give a use of sodium hydroxide

Answer 13

Making bleach and soap

Question 14

Which 4 ions are in sodium chloride solution?

Answer 14

Na+
OH-
H+
Cl-

Question 15

Electrolysis of brine: give the half equation at the anode

Answer 15

2Cl- –> Cl2 + 2e

Question 16

Electrolysis of brine: give the half equation at the cathode

Answer 16

2H+ + 2e- –> H2

Question 17

What is bauxite and what compound does it mainly contain?

Answer 17

An ore that contains aluminium oxide

Question 18

Extraction of aluminium: why is cryolite used?

Answer 18

To lower the melting point so less energy is needed

Question 19

Extraction of aluminium: why do the anodes have to be replaced regularly?

Answer 19

The oxygen produced reacts with carbon anodes to produce carbon dioxide so they burn away.

Question 20

Extraction of aluminium : what is missing from this half equation?
Al3+ + _____ –> Al

Answer 20

3e-

Question 21

Extraction of aluminium: what is missing from this half equation?
2O2- -> O2 + ______

Answer 21

4e-

Question 22

Extraction of aluminium: what is produced at the anode and cathode?

Answer 22

Anode- oxygen

Cathode- aluminium

Question 23

Electrolysis of MOLTEN SODIUM CHLORIDE: what is produced at the anode and cathode?

Answer 23

Anode- chlorine

Cathode- sodium

Question 24

Electrolysis of copper chloride solution: what is produced at the anode and cathode?

Answer 24

Anode- chlorine | Cathode- copper

Question 25

Electrolysis of copper sulphate solution: what is produced at anode and the cathode?

Answer 25

Anode- oxygen | Cathode- copper

Question 26

Which substance produces zinc at the cathode and chlorine at the anode?

Answer 26

Molten zinc chloride

Question 27

Define electrolysis

Answer 27

The process that uses electricity to break down ionic compounds into elements.

Question 28

The substance that breaks down is called the...?

Answer 28

Electrolyte

Question 29

What must be done to ionic compounds before they can be electrolysed?

Answer 29

It must be dissolved or melted

Question 30

What are the electrodes made from?

Answer 30

An inert substance that does not react with the products

Question 31

Fill in the gap: | The ions in the electrolyte move to the electrodes where they are discharged to produce ________

Answer 31

Elements

Question 32

Fill in the gaps: | Positively charged _______ are attracted to the _________ electrode where they form ________ or _________.

Answer 32

Ions Negative Metals or hydrogen

Question 33

Fill in the gaps: Negatively charged ________ are attracted to the _________ electrode where they lose their charge to form non- metallic elements.

Answer 33

Ions | Positive

Question 34

An ion always moves to the ?

Answer 34

Oppositely charged electrode

Question 35

Fill in the gaps: When positively charged ions reach the ________ electrode they ________ electrons to become neutral atoms. This is called?

Answer 35

Negative Gain Reduction

Question 36

At the positive electrode, negative ions ______ electrons to become neutral atoms. This is called?

Answer 36

Lose Oxidation

Question 37

What's the half equation at the anode for lead bromide?

Answer 37

2Br--> Br2 + 2e-

Question 38

What's the half equation at the cathode for lead bromide?

Answer 38

Pb2+ + 2e- --> Pb

Question 39

How is aluminium manufactured?

Answer 39

Aluminium oxide is electrolysed

Question 40

What forms at the cathode and anode during the extraction of Aluminium?

Answer 40

Anode- oxygen | Cathode - aluminium

Question 41

What products do we get when we electrolyse brine?

Answer 41

Chlorine gas, hydrogen gas, sodium hydroxide solution

Question 42

Why is hydrogen produced when sodium chloride is electrolysed?

Answer 42

The solution contains hydrogen ions which are discharged in preference to sodium ions because sodium is more reactive than hydrogen.

Question 43

Why is the electrolysis of brine an important industrial process?

Answer 43

It's three products have many uses

Question 44

Why can we electroplated objects?

Answer 44

To improve their appearance , protect their surface, and use smaller amounts of precious metals.

Question 45

Why,are some knives, forks and spoons silver plated?

Answer 45

To make them look attractive, to protect the metal from corrosion and to reduce costs.