AQA Combined Chemistry 5.4 Flashcards

Revision for Paper 1

1
Q

Why is cryolite used in the electrolysis of aluminium oxide?

A

To lower the melting point of aluminium oxide (to save energy and costs)

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2
Q

In the electrolyis of lead bromine, what collects at:

a) the posistive electrode (the anode)?
b) the negative electrode (the cathode)?

A

a) Bromine

b) Lead

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3
Q

To which electrod are negative ions attracted to?

A

Positive electrode

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4
Q

In electrolysis, what is the negative electrode called?

A

Cathode

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5
Q

To which electrode are positive ions attracted to?

A

Negative electrode

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6
Q

In electrolysis what is the positive electrode called?

A

Anode

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7
Q

What is the pH range of acids?

A

0-6

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8
Q

What is the pH range for alkalis?

A

8-14

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9
Q

What is the pH of a neutral solution?

A

7

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10
Q

Name the ‘salt’ produced when the following chemicals react:

a) Sodium carbonate + nitric acide
b) Magnesium oxide + sulfuric acid
c) Iron hydroxide + hydrochloric acid

A

a) Sodium nitrate
b) Magnesium sulfate
c) Iron chloride

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11
Q

Write the formulae of the following salts using the formulae of ions provided below:

a) Sodium Chloride
b) Magnesium Chloride

A

a) NaCl

b) MgCl2

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12
Q

What type of reaction is shown by the equation below?

magnesium + oxygen - magnesium oxide

A

Oxidation

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13
Q

What is the name for the reaction the gaining of oxygen?

A

Oxidation

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14
Q

What 2 non-metlas are often included in the reactivity series?

A

Hydrogen and Carbon

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15
Q

What is the name for the reaction that involves the removal of oxygen?

A

Reduction

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16
Q

Put the following elemetnts in order of reactivity from least to most reactive:
iron / lithium / zinc / copper / potassium / calcium / sodium / magnesium

A

copper - iron - zinc - magnesium - calcium - lithium - sodium - potassium

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17
Q

What chemical reaction is shown by the equation below to extract iron from iron oxide?
Iron oxide + carbon - iron + carbon dioxide

A

Reduction

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18
Q

What type of seperation process would you use to seperate a soluble salt?

A

Crystallisation

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19
Q

What type of seperation process would you use to seperate an insoluble salt?

A

Filtration

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20
Q

Why must aluminium be extracted by electrolysis?

A

It is more reactive than carbon

21
Q

Why does the positive electrode have to be regularly replaced in the extraction of aluminium oxide?

A

Because oxide ions react with the carbon electrode
Releasing CO2
Meaning the electrodes gradually degrade

22
Q

Write an ionic equation for each of teh displacement reactions below:

a) Mg + CuSO4 - Cu + MgSO4
b) Fe + CuCl2 - Cu + FeCl2

A

a) Mg (s) + Cu2+ (aq) - Cu (s) + Mg2+ (aq)

b) Fe (s) + Cu2+ (aq) - Cu (s) + Fe2+ (aq)

23
Q

In the following equation, state which species are oxidised and which are reduced?
Mg (s) + 2HCl (aq) - MgCl2 (aq) + H2 (g)

A
  • Magnesium atoms are oxidised

- Hydrogen atoms are reduced

24
Q

Fill in the blanks:

a) Oxidation is the _____ of electrons

b) Reduction is the _____ of electrons

A

a) loss

b) gain

25
Q

In the following equation, state which species are oxidised and which are reduced?
2Fe2O3 + 3C - 4Fe + 3CO2

A
  • 2Fe2O3 is reduced

- 3C is oxidised

26
Q

During electrolysis, what happens to ions at the:

a) Cathode?
b) Anode?

A

a) Ions gain electrons and turn into atoms (reduction)

b) Ions lose electrons and turn into atoms (oxidation)

27
Q

Write half equations at the anode and cathode for the electrolysis of water

A
  • Anode: 4OH- — 4e- = O2 + 2H2O

- Cathode: 2H+ ++ 2e- = H2

28
Q

Explain why the reaction below is a redox reaction

Zn (s) + 2HCl (aq) - ZnCl2 (aq) + H2 (g)

A
  • Zinc atoms are oxidised
  • Hydrogem atoms are reduced
  • Hence reduction and oxidation happen at the same time so it’s called a redox reaction
29
Q

Write the half equations at the anode and cathode for the electrolysis of lead bromide

A
  • Anode: 2Br- – 2e- = Br2

- Cathode: Pb2+ ++ 2e- = Pb

30
Q

As the hydrogen ion concentration of a solution increases by a factor of 10, what happens to the pH of the solution?

A

The pH decreases by 1 unit

31
Q

If you compared the pH of a 1M Strong Acid and a 1M Weak Acid, which would have a high pH and why?

A

The weaker acid will have the higher pH because it only partially ionises in water

32
Q

What is a ‘weak’ acid?

A

An acid that is only partially ionised in water

33
Q

Give 2 examples of strong acids and 2 examples of weak acids

A

Strong acids include: Hydrochloric, Nitric and Sulfuric

Weak acids include: Carbonic, Ethanoic and Citric

34
Q

Name the ion found in acidic solutions

A

Hydrogen ion, H+

35
Q

Name the ion found in alkaline solutions

A

Hydroxide ion, OH-

36
Q

Write an ionic equation for neutralisation

A

H+ (aq) + OH- (aq) = H2) (l)

37
Q

Why does a metal compound have to be molten or dissolved for electrolysis to work?

A

Because the ions need to be free to flow

38
Q

What is the name for the reaction when an acid reacts with an alkali to make a salt + water?

A

Neutralisation reaction

39
Q

When there are several ions in solution, which ion will collect:

a) at the anode?
b) at the cathode?

A

a) Hydrogen is produced if the metal is more reactive than Hydrogen
b) Oxygen is produced unless the solution contains halide ions, then the halogen is produced

40
Q

What is the name for the liquid that contains the ions the electrolysis process?

A

Electrolyte

41
Q

Why is gold found naturally in the Earth, but other metals are locked up in compounds?

A

Gold is unreactive

42
Q

Describe how you would make a pure, dry sample of a soluble salt using an insoluble base and an acid

A
  • add base in excess to acid
  • filter excess base
  • crystallisation; to seperate salt from its solution
43
Q

If an atom is very reactive, is it more or less likely to turn into an ion?

A

More likely

44
Q

Why can’t aluminium be extracted by reduction with carbon?

A

Aluminium is more reactive than carbon

45
Q

Complete the general equation:

Metal + Acid - ___ + ___

A

Metal + Acid - Salt + Hydrogen

46
Q

Complete the general equation:

Metal + Water - ___ + ___

A

Metal + Water - Metal hydroxide + Hydrogen

47
Q

Complete the general equation:

Acid + Metal Carbonate - ____ + _____

A

Acid + Metal Carbonate - Salt + Water + carbon dioxide

48
Q

Complete the general equation:

Acid + Metal oxide - ____ + ____

A

Acid + Metal oxide - Salt + Water