Electrolysis CS

Question 1

When can an ionic compound conduct electricity?

Answer 1

When it is melted or dissolved.

Question 2

What is an electrolyte?

Answer 2

A liquid or solution that is able to conduct electricity.

Question 3

What happens when an electric current is passed through an electrolyte?

Answer 3

The ions move to the electrodes.

Question 4

What is the cathode?

Answer 4

Negative electrode.

Question 5

What is the anode?

Answer 5

Positive electrode.

Question 6

Which electrode are positive ions attracted to?

Answer 6

Negative electrode.

Question 7

Which electrode are negative ions attracted to?

Answer 7

Positive electrode.

Question 8

What happens at the electrode?

Answer 8

The ions are discharged at the electrodes producing elements.

Question 9

What happens when a simple ionic compound is electrolysed?

Answer 9

The metal forms at the cathode and the non-metal is produced at the anode.

Question 10

.When is electrolysis used to extract metals?

Answer 10

.When the metal is too reactive to be extracted by reduction with carbon, or if the metal reacts with carbon.

Question 11

.What are the problems of extracting metals using electrolysis?

Answer 11

.Large amounts of energy are needed to melt the compound and produce the electrical current.

Question 12

.How is aluminium extracted using electrolysis?

Answer 12

.The aluminium oxide is melted and mixed with cryolite. The aluminium ions move to the negative electrode to make aluminium and the oxygen ions move to the positive electrode to react with the carbon electrode and make carbon dioxide.

Question 13

.Why is a mixture used as the electrolyte for the extraction of aluminium?

Answer 13

.The cryolite lowers the melting point of aluminium oxide.

Question 14

.Why must the positive electrode be replaced during the electrolysis of aluminium?

Answer 14

.The oxygen reacts with the carbon in the electrode burning it away.

Question 15

.During the electrolysis of an aqueous solution what does the ion discharged at the electrode depend on?

Answer 15

.The reactivity of the elements involved.

Question 16

.What is formed on the negative electrode if the metal is more reactive than hydrogen?

Answer 16

.Hydrogen

Question 17

.When is oxygen made at the positive electrode?

Answer 17

.When the solution does not contain halide ions.

Question 18

.What happens at the cathode? (HT Only)

Answer 18

.Positive ions gain electrons and are reduced.

Question 19

.What happens at the anode? (HT Only)

Answer 19

.Negative ions lose electrons and are oxidised.

Question 20

What is electrolysis?

Answer 20

Using electricity to break down a substance

Question 21

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

Answer 21

The ions become free to move around

Question 22

What is the name for the positive electrode?

Answer 22

The anode

Question 23

What is the name for the negative anode?

Answer 23

The cathode

Question 24

Do positive ions move to the anode or the cathode?

Answer 24

Cathode

Question 25

Do negative ions move to the anode or the cathode?

Answer 25

Anode

Question 26

At which electrode would Zn²+(aq) turn into Zn(s)?

Answer 26

Cathode (needs to gain electrons)

Question 27

At which electrode would Cl?(aq) turn into Cl?(g)?

Answer 27

Anode (needs to lose electrons)

Question 28

Balance the equation: Al³? + e? ? Al

Answer 28

Al³? + 3e? ? Al

Question 29

Balance the equation: Cl? ? Cl? + e?

Answer 29

2Cl? ? Cl? + 2e?

Question 30

Balance the equation: O²? ? O? + e?

Answer 30

2O²? ? O? + 4e?

Question 31

What will be the products for the electrolysis of molten iron bromide?

Answer 31

Iron and bromine

Question 32

What will be the products for the electrolysis of molten zinc oxide?

Answer 32

Zinc and oxygen

Question 33

For the extraction of which metals is electrolysis needed?

Answer 33

Ones more reactive than carbon, e.g. aluminium

Question 34

What are the two main disadvantages of using electrolysis to extract metals?

Answer 34

Requires a large amount of energy to melt the compounds and to produce the necessary electricity

Question 35

Why is aluminium oxide mixed with cryolite when extracting aluminium?

Answer 35

To lower the melting point

Question 36

What is produced at the anode and cathode in the electrolysis of aluminium oxide?

Answer 36

Aluminium at the cathode and oxygen at the anode

Question 37

Why does the anode need to be replaced in the electrolysis of aluminium oxide?

Answer 37

The oxygen reacts with the carbon electrode to produce carbon dioxide.

Question 38

In the electrolysis of sodium chloride solution, what are the products?

Answer 38

Chlorine gas and hydrogen gas

Question 39

Why is sodium not produced in the electrolysis of sodium chloride solution?

Answer 39

It is more reactive than hydrogen so hydrogen is produced instead.

Question 40

What is produced at the anode in electrolysis of solutions?

Answer 40

Either a halogen or oxygen (when there is no halogen present)