C6 Electrolysis

Question 1

OilRig

Answer 1

Oxidation
Is 
Loss
Reduction
Is 
Gain

(In terms of electrons)

Question 2

How do yo extract a metal with carbon?

Using carbon reduction

Answer 2

1) You can only do this with metals that are below carbon in the reactivity series
2) The ore is reduced using carbon
3) The carbon gains the oxygen atom so it has been oxidised

Question 3

What is a redox reaction?

Answer 3

A reaction which contains an atom loosing and a different atom gaining a electron/s at the same time

Reduction and Oxidation must happen at the same time.

Question 4

Give an example of a redox reaction

Answer 4

Displacement reactions (when a more reactive atom kicks out a less reactive one in a compound)

Question 5

What is going through reduction and oxidation in a displacement reaction?

Answer 5

The metal ion is being reduced (the metal in the coupound)

The metal ATOM is oxidising (the metal that is not in the compound)

Question 6

What is an ionic equasion?

Answer 6

An equasion that only shows the particals that react

Question 7

What is a spectator in an equasion?

Answer 7

Something that doesn’t change

Ionic equasions take out the spectators

Question 8

What is electrolysis?

Answer 8

When you seperate 2 solutiions in a electrolyte (an aq solution or a disolved ionic compound)

Question 9

How does electrolysis work?

Answer 9

The positive ions move towards the cathods (they are reduced) by the negative electric electrons moving through it

The negative ions move towards the anode (they are oxidised) …

The elements become uncharged and are discharged from the electrolyte (solition)

Question 10

Why can’t a ionic solid be electrolised?

How can youfix this?

Answer 10

Because the atoms are in a fixed place and arn’t able to move around to the cathode/anode

By melting the slid (molten)

Question 11

What is a way to extract metals from there ores?

Answer 11

Electrolysis

Question 12

Why is using electrolysis to extract metals from ores bad?

Why might you need to do it?

Answer 12

It is expensive to get the energy to melt the ores and to run energy through them.

The metal is more reactive to be reduced by carbon therefore

Question 13

Why does the molton solution conduct electiclrity?

Answer 13

It contains free electeons

Question 14

When electolysis is done on alumninion what is done it it? Why?

Answer 14

It is mixed in cryolite solution to lower it’s melting point so that it is cheeper and easier to melt into a molten solution

Question 15

What happens at each electrode when electrolysis with aluminion happens?

Answer 15

Cathode (negative electode) Al3 + 3e- = Al
(Reduction)(the metal)

Anode 2O*2- =O+4e-
(Oxidisation)(non metal)

Question 16

Why do the electrodes in the electolysos of alimunin need to be swapped out regualy?

Answer 16

Because the oxygen being produced reacts with the andoe made out of carbon. This degrades the carbon so it need to be replaced regauly

Question 17

In the electolysis of aluminion what are the electrodes made out of?

Answer 17

Graphite (carbon)

Question 18

In the electrolysos of an aq solution when is H+ions produced?

Answer 18

Hydrogen is produced at the cathode if the metal is more reactive than hydrogen

Question 19

In the electrolysos of an aq solution what is usually prodiced at the anode?

What is the exception?

Answer 19

O2

If the aq solution contains halide ions(halogen), then the halogen will be produced at the anodes eg F*-

Question 20

What does H^2Osplit into?

Answer 20

H+ and OH-

Question 21

In the electrolysos of an aq solution Why are there 2 different ions competing at each electrode?

Answer 21

You have the ions of the water and the ions of the ionic compound

Question 22

What are the half equasions for the electrolysis of Copper III Sulfate?

Answer 22

Copper is less reactive than hydrogen so copper is produced

Cathode - Cu2+ + 2e- = Cu

There are no halide ions so oxygen and water are produced

Anode - 4OH- = O2 +2H2O (water) + 4e-

Question 23

What are the half equasions of Sodium Chloride?

Answer 23

Sodium is more reactive than hydrogen so hydrogen is produced

Cathode 2H+ + 2e- = H*2

Chloride ions (halide ions) are present so the halogen is produced

Anode 2Cl- = Cl*2 + 2e-

Question 24

Why does the reaction of H^2O have a special arrow symbol?

Answer 24

Because it is reversable

Question 25

What happens at the Cathode is H+ ions and metal ions are present?

Answer 25

Hydrogen gass will be produced if the metal ions form an element that is more reactive than hydrogen A layer of pure metal will be produced if not (if the metal ions form an element that is less reactive than hydrogen

Question 26

What happens at the anode if OH- ions are present?

Answer 26

Oxygen will produced However if there is a halide present then the halide will be produced not oxygen

Question 27

How can you lest for hydrogen?

Answer 27

The squeeky pop test with a lighted splint

Question 28

How can you test for oxygen?

Answer 28

A substance that contains oxygen will relight a glowing splint

Question 29

How can you test for chlorine?

Answer 29

It will bleach litmus paper white

Question 30

What need to be the same woth each half equacion?

Answer 30

The amount of electrons

Question 31

Give an example of a displacemnt reaction?

Answer 31

Fe(s) + CuSO^4(aq) = FeSO^4(aq) + Cu(s) Iron + Copper Sulfate = Iron Sulfate + Copper

Question 32

What are the ionic equasions of the displacement reaction?

Answer 32

Fe = Fe2+ +2e- Cu2+ + 2e- = Cu

Question 33

In a displacement reaction what is oxidised?

Answer 33

The metal ion

Question 34

What is an ionic equasion?

Answer 34

An equasion that just shows the bits that change

Question 35

What does electrolysis mean? (Litteraly)

Answer 35

"Splitting up with electricity

Question 36

What happens during electrolysis?

Answer 36

Electricity is passed through a molten or disolved ionic compound The ions then move towards the electrodes where they react and the coupound decomposes The positive ions move towards the cathode and gain electrons (reduction) The negative ions move towards the anode wherw they loose electrons (oxidised) This creates a flow of charge throught he electrolyte At the anode and cathode ions gain/loose electrons and form un charged elements and are discharged.

Question 37

What is the electrolyte?

Answer 37

The solution which electolysis is happening in

Question 38

Where do positive metal ions go?

Answer 38

The cathode

Question 39

Where do negative non metal ions go

Answer 39

The anode

Question 40

Where does the non metal go?

Answer 40

The anode

Question 41

Where does the metal go?

Answer 41

The cathode

Question 42

Why might you use electrolysis to extract an ore?

Answer 42

If the metal is too reactive to be reduced with carbon

Question 43

What are the disadvantages of using elctrolysis?

Answer 43

It is expensive as it requires a lot of energy

Question 44

What is aluminium extracted from? How?

Answer 44

From the ore bauxite using electrolysis

Question 45

What is aluminium mixed with? Why?

Answer 45

Cryolite To lower the melting point

Question 46

Why does the melting point of aluminium need to be lowered?

Answer 46

To make it cheaper to melt (less energy required). It needs to be melted so that the molten form will contain free ions and therefore will conduct electricity

Question 47

What happens at the negative electrode (the anode)? | In the electorysis of aluminium

Answer 47

Al3+ ions go there where they pick up 3 electrons and turn back into neutral Al atoms. They then sink to the bottom of the tank

Question 48

What hapens at the positive electrode (the cathode)? | In the electorysis of aluminium

Answer 48

The O2- ions go to the positive electron where they loose two electrons. The neitral oxygen atoms combine to form O^2 molecules

Question 49

Why do the anode? need to be replaced often?

Answer 49

It is made of Carbon and therefore it reacts with the oxygen. This degrades it

Question 50

What is the half equasion at the negative electrode? | In the electorysis of aluminium

Answer 50

Al3+ + 3e- = Al

Question 51

What is the half equasion at the positive electode? | In the electorysis of aluminium

Answer 51

2O2- = O^2 + 4e-

Question 52

What is the overall word equasion? | In the electorysis of aluminium

Answer 52

Aluminium oxide = aluminium + oxygen

Question 53

What is the overall symbol equasion? | In the electorysis of aluminium

Answer 53

2Al^2O^3(l) = 4Al(l) + 3O^2(g)