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Chemistry > Unit 10, 11, 12 & 13 - Electrolytic Processes/ Obtaining And Using Metals/ Transition Metals/ Alloys And Corrosion > Flashcards

Unit 10, 11, 12 & 13 - Electrolytic Processes/ Obtaining And Using Metals/ Transition Metals/ Alloys And Corrosion Flashcards

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1
Q

What can acidified water be broken down into by electrolysis?

A

Hydro peen and oxygen

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2
Q

What is electrolysis?

A

Using an electrical current to break down substances

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3
Q

What is an electrolyte?

A

An ionic substance with freely moving ions and can conduct electricity

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4
Q

What happens to the electrolytes during electrolysis?

A

They move to the opposite charged electrode

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5
Q

What are the electrodes and which is which charge?

A

Anode: positive
Cathode: negative

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6
Q

What electrolytes move to which electrode?

A

Cation —> cathode

Anion —> anode

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7
Q

What is the acronym for electrodes

A

PANIC

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8
Q

What happens at each electrode?

A

Negative ions lose electrons, positive ions gain electrons

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9
Q

What is the acronym for oxidation and reduction?

A

OIL RIG

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10
Q

What is oxidisation? (Electrons)

A

Losing electrons

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11
Q

What is reduction (electrons)

A

Gaining electrons

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12
Q

Why are there chemical changes at the electrodes?

A

They change from charged ions to atoms or molecules

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13
Q

What do half equations show? (Electrolysis)

A

What happens at each electrode

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14
Q

What happens during electrolysis of copper sulphate solution when using a pure copper electrode and an impure copper electrode?

A

The copper at the impure electrode loses 2 electrons each, the copper ions them dissolve in the solution and move to the negative electrode and become pure copper. The impurities from the other electrode gathers at the bottom. The mass of the impure electrode decreases and the other increases

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15
Q

Explain the core practical - electrolysis of copper sulphate solution

A

Label a piece of copper the anode and another cathode. Measure the masses. Set up an electrolysis circuit and turn on power to 0.2 A. Leave for 20 minutes. Turn off power, wash in distilled, dip in propane and let the propane evaporate. Measure the masses of the electrodes. Repeat for different currents.

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16
Q

What type of electrodes do molten or dissolved ionic salts use?

A

Inert (unreactive) electrodes

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17
Q

When a molten salt is electrolysed, how are the ions discharged as?

A

Atoms or molecules

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18
Q

During electrolysis, what will the salt always decompose into?

A

It’s elements

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19
Q

Which elements of a salt are produced at which electrode?

A

Metal at cathode

Non metal at anode

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20
Q

When a solution is dissolved in water, what is important to remember about the ions?

A

There will be the dissolved ions as well as H+ and OH- ions

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21
Q

Electrolysis: copper chloride in aqueous solution, if the copper chloride decomposes but the water doesn’t change, what is the overall equation?

A

CuCl2(aq) —> Cu(s) + Cl2(g)

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22
Q

Electrolysis: sodium chloride aqueous solution, sodium chloride decomposes to form hydrogen and chlorine, sodium and hydroxide ions remain in solution, what is overall equation?

A

2NaCl(aq) + 2H2O(l) —> H2(g) + Cl2(g) + 2NaOH(aq)

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23
Q

What is the rule for the products formed at the cathode?

A

Least reactive ion

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24
Q

What is the rules for the product formed at the anode?

A

Halides (chlorine, bromine, iodine) > hydroxide > other ions

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25
Q

What are the 5 least reactive ions (from hydrogen down)

A

Hydrogen, copper, silver, gold, platinum

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26
Q

What is the reactivity series?

A

A list of metals in order of reactivity, most reactive at top

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27
Q

What do metals that react with cold water form?

A

Hydrogen and a metal hydroxide

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28
Q

What do metals that react with steam form?

A

Hydrogen and a solid metal oxide

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29
Q

What do metals that react with dilute acids form?

A

Hydrogen and a salt solution

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30
Q

Wha pr happens to a metal when it reacts

A

They lose electrons

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31
Q

How can the reactivity series help us tell if a reaction will take place

A

Each metal will react with compounds of the metals below it.

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32
Q

What is a displacement reaction?

A

When a metal reacts with a metal compound. The metals swap places

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33
Q

Why can displacement reactions only work one way?

A

Because the metal compound must be less reactive than the metal

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34
Q

What are spectator ions?

A

Ions that don’t change in a reaction

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35
Q

How do you write an ionic equation?

A

Remove any ions that remain the same throughout and include charges

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36
Q

What is a redox reaction?

A

A reaction where one substance is oxidised and another is reduced

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37
Q

What is extraction?

A

The process of obtaining a metal from its compound

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38
Q

What is an ore?

A

A rock that contains enough of a compound to extract a metal for profit

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39
Q

How is iron extracted from its ore?

A

Heating the iron oxide with carbon

40
Q

When does heating the ore result in the metal?

A

When the metal is below carbon in the reactivity series

41
Q

When is electrolysis used to extract metals?

A

When the metal is above carbon in the reactivity series

42
Q

What does electrolysis involve?

A

Passing electricity through a molten ionic compound to decompose it into its elements

43
Q

Why is electrolysis expensive?

A

A lot of energy is needed to keep metal oxides molten

44
Q

What is bioleaching?

A

A method where bacteria is grown on a low grade ore which produces a solution containing the metal ions called a leachate. The metal is extracted from this by displacement

45
Q

What is phytoextraction

A

A process where plants are grown that absorb metal compounds, these are burnt to form ash and the metal is extracted

46
Q

Give 2 advantages of both bioleaching and phytoextraction

A

No harmful gases produced

Causes less damage to landscape than mining

47
Q

Give 1 disadvantage for both bioleaching and phytoextraction

A

Very slow

48
Q

What must be removed in order to obtain the metal from its oxide

A

Oxygen

49
Q

During electrolysis using aluminium oxide and graphite electrodes, what does the oxygen react with to form

A

The graphite electrodes to form carbon dioxide

50
Q

What is rusting

A

The corrosion of iron that requires water and oxygen

51
Q

When does corrosion happen

A

When a metal reacts with oxygen

52
Q

Why is gold used for jewellery

A

It doesn’t corrode

53
Q

Give 3 advantages of recycling metals

A

Natural reserves of metal ores last longer
Less pollution produced as sulphur dioxide is formed when they are extracted from ores
Less waste metal ends up in landfill sites

54
Q

Give 3 disadvantages of recycling metals

A

Expensive as it uses a lot of energy to melt the metal
Transporting the metal
Sorting the metals

55
Q

What does LCA stand for

A

Life cycle assessment

56
Q

What does the LCA help to decide

A

Whether it is worthwhile to manufacture and recycle a product

57
Q

What is a reversible reaction

A

A reaction where the products can react to reform the reactants

58
Q

What is a dynamic equilibrium

A

When a reaction is reversible so 2 reactions are constantly reacting but at a rate where the substances remain in balance

59
Q

What must happen for a dynamic equilibrium to occur

A

It must be in a closed system

60
Q

What can alter the equilibrium position

A

Temperature, pressure and concentration

61
Q

If the temperature is increased, which way does the equilibrium move

A

Towards to endothermic as it takes in the extra heat

62
Q

Which way does the equilibrium move if the pressure is increased

A

Towards to low pressure side to take in the extra molecules

63
Q

Which direction does the equilibrium move if the concentration is increased

A

To the side that uses up the extra substance

64
Q

What are transition metals used for

A

Construction, jewellery, vehicles

65
Q

Why is copper used for electrical wiring?

A

It is ductile and a good conductor of electricity

66
Q

What is iron used for

A

Making buildings, bridges, cars

67
Q

Do transition metals have higher or lower densities and melting points compared to normal metals

A

Her

68
Q

Give an exception for transition metals in terms of melting points

A

Mercury, liquid at room temp

69
Q

What type of compounds do transition metals form

A

Coloured

70
Q

Give a use of transition metals in terms of chemical reactions

A

Used as catalysts

71
Q

What is a tarnish

A

When metals form a thin layer when they oxidise which stops oxygen reaching the metal

72
Q

What is corrosion

A

When a metal continues to oxidise and so the metal becomes weaker

73
Q

What is rusting

A

The corrosion of iron or steel

74
Q

What is the product when iron reacts with oxygen and water

A

Rust, hydrated iron oxide

75
Q

What is desiccant powder used for

A

Preventing rust by absorbing water vapour

76
Q

How is oxygen kept away from rusting objects

A

By storing the metal in an unreactive atmosphere of nitrogen or argon

77
Q

Give 2 ways of preventing rusting

A

Painting, piling

78
Q

What is sacrificial protection

A

A method of preventing rust by attaching a piece of magnesium or zinc to the iron object as it reacts more easily with oxygen

79
Q

What is electroplating

A

Coating the surface of a metal with a thin layer of another metal

80
Q

Why might something be electroplated with silver or gold

A

They are expensive but attractive

81
Q

Why might something be electroplated with chromium

A

It resists corrosion and stops air and water reaching the steel, prevents rusting

82
Q

Why might connectors be gold-plated

A

It is the third best electrical conductor but doesn’t tarnish as much

83
Q

How does electroplating with silver work

A

Set up electrolysis equipment (anode, cathode, electrolyte)
Anode must be silver plating metal and the electrolyte must have silver ions
The silver ions in the electrolyte move towards the cathode where they get electrons and become atoms
The silver at the anode loses electrons to become ions which move to the cathode

84
Q

What is galvanising

A

When iron and steel objects are protected from rusting by coating them with zinc

85
Q

How does galvanising protect the metal

A

Sacrificial protection and the zinc papacy’s as a waterproof layer

86
Q

How can galvanising be carried out (2)

A

Electroplating, dipping in molten zinc

87
Q

Why is tin used for the insides of food cans

A

It doesn’t react with air or water are room temp

88
Q

What is an alloy

A

A mixture of a metal element with one or more other elements

89
Q

How are alloy steels made

A

By deliberately adding other elements to iron

90
Q

What is a good and different characteristic of stainless steel compared to other steels

A

It resists rusting

91
Q

What does stainless steel contain to help it be resistant to air and water

A

A layer of chromium oxide

92
Q

What do ‘tool steels’ contain

A

Tungsten and molybdenum

93
Q

What makes a steel stronger

A

Increased carbon content

94
Q

Why are alloys stronger than pure metals

A

In pure metal, all atoms are the same size in layers which can move around but in an alloy, the atoms are different sizes so the layers can’t slide

95
Q

Give an example of a chemical property

A

Resistance to corrosion

96
Q

Give an example of a physical property

A

Ability to conduct electricity

97
Q

What metal is normally chosen for electrical wiring

A

Copper

Chemistry (12 decks)

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