C6 Electrolysis

Question 1

Why cant solid ionic compounds conduct electricity?

Answer 1

This is because the ions are locked in place meaning they are NOT FREE TO MOVE, therefore a charge cannot be carried through the structure

Question 2

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

Answer 2

The forces of attraction are broken and the ions are now free to move - therefore now they are able to conduct electricity

Question 3

What are liquids or solutions in electrolysis called?

Answer 3

Electrolytes

Question 4

What does molten mean?

Answer 4

Melted

Question 5

What are electrodes made up of usually?

Answer 5

A conducting material like graphite or a metal

Question 6

What is the negative electrode called?

Answer 6

Cathode

Question 7

What is the positive electrode called?

Answer 7

Anode

Question 8

What is the Cathode?

Answer 8

This is the negative electrode which is covered in electrons which are coming from the power pack and this is attached to the negative terminal of a power pack.

Question 9

What is the anode?

Answer 9

This is the positive electrode, which has a lack of electrons, this is connected to the positive terminal of the power pack.

Question 10

What are positive ions attracted to and why?

Answer 10

They are attracted to the cathode (negative electrode), this is because opposite charges attract, here the ions GAIN ELECTRONS to form atoms.

Question 11

What is reduction?

Answer 11

Gain of electrons

Question 12

What are negative ions attracted to and why?

Answer 12

They are attracted to the positive electrode because opposite charges attract. Here ions LOSE ELECTRONS to form atoms.

Question 12

What is gaining electrons called in electrolysis?

Answer 12

Reduction

Question 13

What is oxidation?

Answer 13

Losing electrons

Question 14

What is losing electrons called in electrolysis?

Answer 14

Oxidation

Question 15

What metals can be extracted with reduction with carbon?

Answer 15

Metals LESS reactive than CARBON can be extracted by REDUCTION with carbon.

Question 16

What metals can be extracted using electrolysis?

Answer 16

Metals MORE reactive than CARBON can be EXTRACTED using ELECTROLYSIS

Question 17

What are 2 things aluminium oxide used to make?

Answer 17

1) Aircrafts
2) Drinkcans

Question 18

What is aluminium extracted from?

Answer 18

Aluminium is extracted from the compound ALUMINIUM OXIDE by ELECTROLYSIS.

Question 19

What does aluminium oxide contain?

Answer 19

Contains Aluminium ions (Al^3+) and the oxide ions (O^2-)

Question 20

What is the equation of aluminium oxide?

Answer 20

Al2O3

Question 21

What is one characteristic of aluminium oxide?

Answer 21

It has a very high melting point

Question 22

What is mixed in with aluminium oxide to lower the melting point?

Answer 22

Cryolite

Question 23

What is cryolite used for in the extraction of aluminium oxide and what does this mean?

Answer 23

Used to lower the melting point of aluminium oxide, this REDUCES the amount of ENERGY needed and SAVES MONEY.

Question 24

What are the electrodes (cathode and anode) made of during the electrolysis of aluminium oxide?

Answer 24

Graphite (carbon)

Question 25

Why is graphite used to make the electrodes for the electrolysis of aluminium oxide?

Answer 25

Graphite is used as it had a VERY HIGH MELTING point meaning we can use it a HIGH temperatures and it is a VERY GOOD CONDUCTOR of ELECTRICITY.

Question 26

What is the equation for aluminium ions?

Answer 26

Al^3+

Question 27

What are aluminium ions attracted to during the electrolysis of aluminium oxide?

Answer 27

Aluminium ions are ATTRACTED to the CATHODE (the NEGATIVE electrode)

Question 28

What are oxide ions attracted to during the electrolysis of aluminium oxide?

Answer 28

Oxide ions are ATTRACTED to the POSITIVE ELECTRODE (anode)

Question 29

What happens at the cathode in the electrolysis of aluminium oxide?

Answer 29

Aluminium ions each GAINS 3 ELECTRONS and forms an ALUMINIUM ATOM

Question 30

What happens at the anode in the electrolysis of aluminium oxide?

Answer 30

Oxide ions each LOSES 2 ELECTRONS to form an OXYGEN ATOM

Question 31

What happens to the aluminium ions in the electrolysis of aluminium oxide?

Answer 31

They get reduce as they each gain 3 electrons

Question 32

What happens to the oxide ions in the electrolysis of aluminium oxide?

Answer 32

The get oxidised as they each lose 2 electrons

Question 33

What is the half equation that shows the reaction at the cathode in the electrolysis of aluminium oxide?

Answer 33

Al^3+ + 3^e- -----> Al

Question 34

What are the 2 half equation that shows the reaction at the anode in the electrolysis of aluminium oxide?

Answer 34

2O^2- -----> O2 + 4e^- 2O^2- - 4e^- ----->O2

Question 35

Why do we double the half equations of the reaction of oxygen at the anode during the electrolysis of alumnium oxide?

Answer 35

Oxygen atoms formed at the ANODE PAIR UP to form the OXYGEN MOLECULES O2, meaning we need to double everything in the half equations.

Question 36

Why much the anode be replaced regularly during the electrolysis of aluminium oxide?

Answer 36

The oxygen molecules produces at the anode REACT WITH THE GRAPHITE (CARBON), forming carbon dioxide gas.

Question 37

What are the 2 reasons why electrolysis is expensive?

Answer 37

1) Melting the compound such as aluminium oxide requires a great deal of ENERGY 2) A lot of energy is required to produce the ELECTRIC CURRENT.

Question 38

What ions move to the cathode and what happens there?

Answer 38

POSITIVE IONS move to the CATHODE (negative electrode) and GAIN ELECTRONS to form atoms.

Question 39

What ions move to the anode and what happens there?

Answer 39

NEGATIVE IONS move to the ANODE (positive electrode) and LOSE ELECTRONS to form atoms.

Question 40

What does aqueous solution mean?

Answer 40

Dissolved in water

Question 41

What happens to water molecules? In the electrolysis of aqueous solutions?

Answer 41

Water molecules IONISE (SPLIT) forming hydrogen ions and hydroxide ions.

Question 42

When is hydrogen produced in the electrolysis of aqueous solutions?

Answer 42

HYDROGEN is produces at the CATHODE if the METAL IS MORE reactive than hydrogen

Question 43

What is an example of whether hydrogen or metal is formed during the electrolysis of aqueous solutions?

Answer 43

Electrolysis of copper sulfate: Copper is LESS REACTIVE than hydrogen so COPPER will be produced at the CATHODE.

Question 44

What is usually used to make the electrodes of the electrolysis of aqueous solutions

Answer 44

PLATINUM is often used as INERT (unreactive) electrodes, as they are unreactive

Question 45

What is the half equation for what is formed at the Cathode during the electrolysis of Copper Sulfate solution? Write it down.

Answer 45

Cu^2+ + 2e^- -----> Cu (above arrow write reduction)

Question 46

What are the 2 half equations for what is formed at the Anode during the electrolysis of Copper Sulfate solution? Write it down.

Answer 46

4OH^- -----> O2 + 2H2O + 4e^- 4OH^- - 4e^- -----> O2 + 2H2O (Write oxidation above both arrows)

Question 47

What is one special condition of the electrolysis of aqueous solutions relating to halogens?

Answer 47

If the aqueous solution contains HALIDE IONS (like chlorine), then the HALOGEN (chlorine) will be produced at the anode.

Question 48

What is the half equation for what is formed at the Cathode during the electrolysis of Sodium Chloride solution? Write it down.

Answer 48

2H^+ + 2e^- -----> H2 (write reduction above arrow)

Question 49

What is are the 2 half equations for what is formed at the Anode during the electrolysis of Copper Sulfate solution? Write it down.

Answer 49

2Cl^- -----> Cl2 + 2e^- 2Cl^- -----> 2e^- -----> Cl2 (Write oxidation above both arrows)

Question 50

What is brine?

Answer 50

Sodium chloride solution