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Chemistry > C6 Electrolysis > Flashcards

C6 Electrolysis Flashcards

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1
Q

OilRig

A 
Oxidation
Is 
Loss
Reduction
Is 
Gain

(In terms of electrons)

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2
Q

How do yo extract a metal with carbon?

Using carbon reduction

A

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

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3
Q

What is a redox reaction?

A

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.

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4
Q

Give an example of a redox reaction

A

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

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5
Q

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

A

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

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

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6
Q

What is an ionic equasion?

A

An equasion that only shows the particals that react

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7
Q

What is a spectator in an equasion?

A

Something that doesn’t change

Ionic equasions take out the spectators

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8
Q

What is electrolysis?

A

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

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9
Q

How does electrolysis work?

A

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)

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10
Q

Why can’t a ionic solid be electrolised?

How can youfix this?

A

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

By melting the slid (molten)

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11
Q

What is a way to extract metals from there ores?

A

Electrolysis

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12
Q

Why is using electrolysis to extract metals from ores bad?

Why might you need to do it?

A

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

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13
Q

Why does the molton solution conduct electiclrity?

A

It contains free electeons

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14
Q

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

A

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

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15
Q

What happens at each electrode when electrolysis with aluminion happens?

A

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

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

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16
Q

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

A

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

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17
Q

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

A

Graphite (carbon)

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18
Q

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

A

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

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19
Q

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

What is the exception?

A

O2

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

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20
Q

What does H^2Osplit into?

A

H+ and OH-

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21
Q

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

A

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

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22
Q

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

A

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-

23
Q

What are the half equasions of Sodium Chloride?

A

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-

24
Q

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

A

Because it is reversable

25
Q

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

A

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

26
Q

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

A

Oxygen will produced

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

27
Q

How can you lest for hydrogen?

A

The squeeky pop test with a lighted splint

28
Q

How can you test for oxygen?

A

A substance that contains oxygen will relight a glowing splint

29
Q

How can you test for chlorine?

A

It will bleach litmus paper white

30
Q

What need to be the same woth each half equacion?

A

The amount of electrons

31
Q

Give an example of a displacemnt reaction?

A

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

Iron + Copper Sulfate = Iron Sulfate + Copper

32
Q

What are the ionic equasions of the displacement reaction?

A

Fe = Fe2+ +2e-

Cu2+ + 2e- = Cu

33
Q

In a displacement reaction what is oxidised?

A

The metal ion

34
Q

What is an ionic equasion?

A

An equasion that just shows the bits that change

35
Q

What does electrolysis mean? (Litteraly)

A

“Splitting up with electricity

36
Q

What happens during electrolysis?

A

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.

37
Q

What is the electrolyte?

A

The solution which electolysis is happening in

38
Q

Where do positive metal ions go?

A

The cathode

39
Q

Where do negative non metal ions go

A

The anode

40
Q

Where does the non metal go?

A

The anode

41
Q

Where does the metal go?

A

The cathode

42
Q

Why might you use electrolysis to extract an ore?

A

If the metal is too reactive to be reduced with carbon

43
Q

What are the disadvantages of using elctrolysis?

A

It is expensive as it requires a lot of energy

44
Q

What is aluminium extracted from?

How?

A

From the ore bauxite using electrolysis

45
Q

What is aluminium mixed with?

Why?

A

Cryolite

To lower the melting point

46
Q

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

A

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

47
Q

What happens at the negative electrode (the anode)?

In the electorysis of aluminium

A

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

48
Q

What hapens at the positive electrode (the cathode)?

In the electorysis of aluminium

A

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

49
Q

Why do the anode? need to be replaced often?

A

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

50
Q

What is the half equasion at the negative electrode?

In the electorysis of aluminium

A

Al3+ + 3e- = Al

51
Q

What is the half equasion at the positive electode?

In the electorysis of aluminium

A

2O2- = O^2 + 4e-

52
Q

What is the overall word equasion?

In the electorysis of aluminium

A

Aluminium oxide = aluminium + oxygen

53
Q

What is the overall symbol equasion?

In the electorysis of aluminium

A

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

Chemistry (16 decks)

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