C6 Electrolysis

Question 1

List the halide ions

Answer 1

Fluoride, chloride, bromide, iodide and astatide

Question 1

What is electrolysis?

Answer 1

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

Question 2

What do ionic compounds have to be in order to be electrolysed?

Answer 2

Molten or in water

Question 3

What is the substance that is broken down called?

Answer 3

The electrolyte

Question 4

What are electrodes made of?

Answer 4

An inert substance

Question 5

What is the positive electrode called?

Answer 5

Anode

Question 6

What is the negative electrode called?

Answer 6

Cathode

Question 7

During electrolysis which electrode do positive ions move towards?

Answer 7

Cathode

Question 8

During electrolysis which electrode do negative ions move towards?

Answer 8

Anode

Question 9

What happens when ions reach the electrode?

Answer 9

They lose their charge and become atoms or molecules

Question 10

Which electrode are metal elements produced at?

Answer 10

Cathode

Question 11

Which electrode are non-metal elements produced at?

Answer 11

Anode

Question 12

At the cathode, if two elements can be produced, which one will be formed?

Answer 12

The less reactive one

Question 13

What ions are attracted to the cathode?

Answer 13

Positively charged metal ions and hydrogen ions

Question 14

What is the order of discharge at the anode?

Answer 14

Halide ions > hydroxide ions > all other negative ions

Question 15

What is given off at the anode when hydroxide ions are discharged?

Answer 15

Oxygen gas

Question 16

Where do you get aluminium from?

Answer 16

The ore bauxite, which is mainly aluminium oxide

Question 17

Why must aluminium be extracted using electrolysis?

Answer 17

Because it is more reactive than carbon

Question 18

What lowers the melting point of aluminium oxide?

Answer 18

Cryolite

Question 19

During the extraction of aluminium, what is produced at the cathode?

Answer 19

Aluminium metal

Question 20

During the extraction of aluminium, what is produced at the anode?

Answer 20

Oxygen gas

Question 21

Why do the carbon anodes regularly need replacing?

Answer 21

Because the react with the oxygen to form carbon dioxide gas

Question 22

What is the half equation for the electrolysis of aluminium at the cathode?

Answer 22

Al^3+ + 3e- > Al (reduction)

Question 23

What is the half equation for the electrolysis of aluminium at the anode?

Answer 23

2O^2- > O2 + 4e- (oxidation)

Question 24

What are the three useful products that you get when you electrolyse sodium chloride solution (brine)?

Answer 24

Chlorine gas, hydrogen gas and sodium hydroxide solution

Question 25

What four ions does sodium chloride solution contain?

Answer 25

Sodium ions, chlorine ions, hydrogen ions and hydroxide ions

Question 26

When electrolysing sodium chloride solution which ions are attracted to the anode?

Answer 26

Chloride ions and hydroxide ions

Question 27

When electrolysing sodium chloride solution what is discharged at the anode and why?

Answer 27

Chloride ions, because they are halide ions

Question 28

What is the half equation for the electrolysis of sodium chloride solution at the anode?

Answer 28

2Cl- > Cl2 + 2e-

Question 29

When electrolysing sodium chloride solution which ions are attracted to the cathode?

Answer 29

Hydrogen ions and sodium ions

Question 30

When electrolysing sodium chloride solution what is discharged at the cathode and why?

Answer 30

Hydrogen ions because sodium metal is more reactive than hydrogen

Question 31

What is the half equation for the electrolysis of sodium chloride solution at the cathode?

Answer 31

2H+ +2e- > H2