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GCSE Chemistry LTS > Chapter 15 Using our Resources (Triple Only) > Flashcards

Chapter 15 Using our Resources (Triple Only) Flashcards

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1
Q

What is the degradation of metal due to prolonged exposure to the environment called?

A

Corrosion

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2
Q

Where does corrosion occur on the metal?

A

Corrosion only occurs on the surface of a metal.

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3
Q

What is rust?

A

Rust is the term used to describe the corrosion of iron.

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4
Q

What is needed for iron to rust?

A

Both oxygen (from the air) and water are needed for iron to rust.

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5
Q

Describe how to investigate the conditions needed for rusting to take place.

A
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6
Q

What compounds are formed in rusting?

A

Iron (III) oxide and hydrated iron (III) oxide

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7
Q

Why does exposure to salt water speed up the rate of rusting?

A

Rusting is a redox process so the presence of sodium and chloride ions speeds up the oxidation and reduction process.

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8
Q

What is the equation for the rusting of iron?

A
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9
Q

What happens to the rust on the surface of a metal over time?

A

The rust will flake off and expose fresh iron to the environment for further rusting to take place.

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10
Q

How can rusting be reduced?

A

Rusting can be reduced by providing a barrier like grease, oil, plastic, a metal coating or paint between the iron and the air and water.

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11
Q

What happens if a barrier to rusting is scratched or removed?

A

Rusting will take place.

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12
Q

What is sacrificial protection?

A

Sacrificial protection involves attaching a metal that is more reactive than iron to the iron. The electrons will be removed from this metal before they will be removed from the iron. This protects the iron from rusting.

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13
Q

Give an example of sacrificial protection.

A

The steel hull of a boat is protected by attaching blocks of zinc.

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14
Q

What is galvanising?

A

Galvanising is the process by which iron is coated with a layer of zinc. It protects the iron in 2 ways.

  1. As a barrier to oxygen and water.
  2. As sacrificial protection as zinc is more reactive than iron.
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15
Q

Give the ion-electron equation for the oxidation of zinc during corrosion.

A

Zn →Zn2+ +2e-

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16
Q

What metals are usually used for sacrificial protection?

A

Zinc, magnesium and aluminium.

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17
Q

What is an alloy?

A

An alloy is a mixture of metals in which the metals are not chemically combined.

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18
Q

Why do alloys usually have different properties than the metals they are made from?

A

The atoms from each metal element are different sizes. This disrupts the orderly alignment of the atoms resulting in different properties.

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19
Q

What properties can be improved by alloying metals?

A

The properties that can be improved by making alloys include:

  1. Increased strength
  2. Increased hardness
  3. More resistance to corrosion
  4. More resistance to extreme temperatures.
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20
Q

Give 2 examples of copper alloys and uses of each.

A
  1. Bronze, made of copper and tin, is used to make ornaments and medals.
  2. Brass, made of copper and zinc, is used in plumbing and carpentry fittings.
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21
Q

What metals are added to gold to make alloys and why?

A

Pure gold is soft and malleable. Copper, zinc and silver are added to gold to make it stronger and tougher.

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22
Q

How can you determine if the gold you have is an alloy?

A

It will be marked with a rating in carats. 24 carat gold is pure gold. 12 carat gold is 50% gold and 50% another metal.

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23
Q

What is cast iron?

A

Cast iron is iron as it comes from a blast furnace. It is 96% iron with small quantities of carbon phosphorus silicon and sulfur.

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24
Q

Why is cast iron not very useful?

A

Cast iron is very brittle.

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25
Q

What needs to happen to cast iron to make it into steel?

A

Cast iron needs the impurities removed and to make it into steel.

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26
Q

What other metals are used in steel alloys?

A

Some steel alloys contain chromium, manganese or nickel.

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27
Q

What are the main properties of high carbon steel?

A

High carbon steel is very hard but very brittle.

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28
Q

What are the main properties of low carbon steel?

A

Low carbon steel is softer than high carbon steel so it is easier to shape.

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29
Q

What is the main property of stainless steel?

A

It is resistant to corrosion.

30
Q

What are polymers made from?

A

Monomers

31
Q

How can you change the properties of the polymer that is produced from a monomer?

A

By changing the reaction conditions such as temperature and pressure.

32
Q

What conditions are needed to produce HD (high density) poly(ethene)?

A

High pressure and a trace of oxygen.

33
Q

What conditions are needed to produce LD (low density) poly(ethene)?

A

A catalyst at 50°C and a slightly raised pressure.

34
Q

What is LDP used for?

A

LDP (low density polythene) is flexible so is used for bags and bottles.

35
Q

What is HDP used for?

A

HDP (high density plastic) is used for water tanks, mouldings and drain pipes because it has a rigid solid structure.

36
Q

Describe the polymer chains in thermosoftening plastics.

A

The polymer chains are entwined with each other and have weak intermolecular forces holding them together.

37
Q

Describe the polymer chains in thermosetting plastics.

A

The polymers in thermosetting plastics have strong cross links between the monomers on different polymer chains.

38
Q

What happens to thermosetting plastic when you heat them?

A

They do not melt but char. This is because they have strong covalent crosslinks.

39
Q

Give 4 properties of glass ceramics.

A

Glass ceramics are:
1. Transparent

  1. Strong
  2. Insulators against heat
  3. Durable
40
Q

How is soda-lime glass made?

A

Limestone is mixed with sand and sodium carbonate until it melts. It then solidifies to form glass.

41
Q

How is borosilicate glass made?

A

Sand and boron trioxide are mixed and heated to make borosilicate glass.

42
Q

How does soda-lime glass differ from borosilicate glass?

A

Soda-lime glass has a lower melting point than borosilicate glass.

43
Q

What are clay ceramics?

A

Clay ceramics are hardened materials made from clay such as bricks, tiles, crockery, sinks, baths and toilets.

44
Q

Give 3 properties of clay ceramics.

A

Clay ceramics are:

  1. Strong
  2. Hard
  3. Resistant to compressive forces
45
Q

How are clay ceramics made?

A

Clay is shaped when wet then heated in a furnace.

46
Q

What are the 2 components of composites?

A

Reinforcement and matrix.

47
Q

What is the purpose of the reinforcement material?

A

It is embedded in the matrix and acts as a binder.

48
Q

Give 3 examples of composite materials and the reinforcements and matrix for each.

A
49
Q

Why is there variation in the properties of composite materials?

A

It depends upon the reinforcement and matrix used.

50
Q

How do the properties of carbon fibres make them suited to their uses?

A

Carbon fibres are strong and have a low weight. This makes them ideal for use in aviation, aeronautics and use in racing bicycles.

51
Q

How do the properties of steel reinforced concrete make it suited to its uses?

A

It gives it tensile and compressive strength to give support in construction.

52
Q

What is the name of the process used to make ammonia?

A

The Haber Process.

53
Q

Where does the hydrogen used in the Haber process come from?

A

It is extracted from methane. Methane is reacted with steam.

54
Q

Where does the nitrogen used in the Haber process come from?

A

It is extracted from the air.

55
Q

Detail the 5 stages in the Haber Process

A

Stage 1: H2 and N2 gases are pumped into the compressor through pipes

Stage 2: The gases are compressed to about 200 atmospheres inside the compressor

Stage 3: The pressurised gases are pumped into a tank containing layers of catalytic iron beads at a temperature of 450°C. Some of the hydrogen and nitrogen react to form ammonia in the following reversible reaction:

N2 (g) + 3H2 (g) ⇌ 2NH2 (g)

Stage 4: Unreacted H2 and N2 and product ammonia pass into a cooling tank. The ammonia is liquefied and removed to pressurised storage vessels

Stage 5: The unreacted H2 and N2 gases are recycled back into the system

56
Q

How does increasing the pressure affect the yield of ammonia in the Haber Process?
(HIGHER ONLY)

A

Increasing pressure increases yield.

57
Q

Why is 200 atmospheres the pressure used if higher pressures would give higher yields?
(HIGHER ONLY)

A

Too much energy is required to pressurise the gases above 200 atmospheres.

58
Q

How does increasing the temperature affect the yield of ammonia in the Haber Process?
(HIGHER ONLY)

A

Increasing temperature increases yield because it increases the rate of reaction but the process is exothermic so lower temperatures increase the amount of ammonia in the reaction mixture at equilibrium. 450°C is a compromise between these 2 factors.

59
Q

What catalyst is used in the Haber Process?
(HIGHER ONLY)

A

Iron

60
Q

What are the 3 elements used to make fertilisers?

A

NPK - nitrogen, phosphorus and potassium.

61
Q

What are fertilisers used for?

A

To increase crop yield.

62
Q

How does nitrogen improve crop yield?

A

Nitrogen promotes healthy leaves for increased photosynthesis.

63
Q

How does potassium increase crop yield?

A

Potassium promotes growth and healthy fruit and flowers.

64
Q

How does phosphorus increase crop yield?

A

Phosphorus promotes healthy roots.

65
Q

What are the 3 water soluble complex ions used to make fertilisers?

A
66
Q

In the production of fertilisers what can ammonia be used to make?

A

Ammonia can be oxidised to make nitric acid.

67
Q

What is the most important ammonium salt used as a fertiliser?

A
68
Q

How is ammonium nitrate made? Write a balanced chemical equation for the production of ammonium nitrate.

A

Ammonium nitrate is produced when ammonia reacts with nitric acid.

69
Q

How is ammonium phosphate made?

A

Reacting ammonia with phosphoric acid

70
Q

How can ammonium sulphate be made in the lab?

A

Sulfuric acid is titrated against ammonia.

71
Q

What is the source of phosphate for the production of fertilisers?

A

Phosphate can be obtained from phosphate rock. These rocks also contain potassium chloride and potassium sulfate so can be used as a source of potassium.

72
Q

How are the useful compounds extracted from the insoluble phosphate rock?

A
  1. Reaction with nitric acid to produce calcium nitrate and phosphoric acid.
  2. Reaction with sulfuric acid to produce calcium phosphate and calcium sulfate.
  3. Reaction with phosphoric acid to produce calcium phosphate also known as superphosphate.

GCSE Chemistry LTS (15 decks)

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