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Chemistry P2 > C15 - Using Our Resources > Flashcards

C15 - Using Our Resources Flashcards

(53 cards)

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1
Q

What is corrosion?

A

The destruction of materials by chemical reactions with substances in the environment

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2
Q

What is an example of corrosion?

A

Rusting

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3
Q

What is necessary for iron to rust?

A

Both air and water

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4
Q

How can rusting be prevented?

A

Keeping oxygen or water away from the iron or steel

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5
Q

How can corrosion be prevented?

A

Applying a coating that acts as a barrier(e.g greasing, painting or electroplating)

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6
Q

Why does aluminium not corrode?

A

Aluminium has an oxide coating that protects it from corrosion

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7
Q

Explain why a bike chain is protected from rusting by oiling it, rather than by painting it

A

Oil lubricates the chain, helping it to move smoothly. Paint just flakes off when the bike is ridden which exposes the steel chain to air and water again

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8
Q

What is electroplating?

A

Using electrolysis to put a thin layer of a metal on the object
1. Cathode is the iron or steel object
2. Anode is the plating metal
3. Electrolyte contains ions of the plating metal
4. It improves the corrosion resistance of metal objects

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9
Q

What is sacrificial protection?

A

Coating that contains a more reactive metal which oxidises more readily than the less reactive metal, once it has corroded away it can simply be replaced

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10
Q

What is an example of sacrificial protection?

A

Zinc used to galvanise iron

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11
Q

What is galvanising?

A

Coating of more reactive metal on less reactive one

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12
Q

What is bronze? + Use

A
  • An alloy of copper and tin
  • Used to make statues, bells and coins
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13
Q

What is brass? + Use

A
  • An alloy of copper and zinc
  • Used to make musical instruments, door knobs, locks and taps
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14
Q

What is gold usually mixed with to make an alloy?

A

Silver, copper and zinc

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15
Q

What is the use of gold?

A

Jewellery

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16
Q

What are the properties of gold?

A
  • Very soft and malleable,
  • very unreactive resisting corrosion,
  • stays shiny
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17
Q

What is 24, 18, 12 and 9 carat gold?

A

24 - Pure gold
18 - 75%
12 - 50%
9 - 37.5%

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18
Q

A piece of gold jewellery is made from 14 carat gold. Calculate the percentage of gold in this alloy.

A

14/24 * 100 = 58%

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19
Q

What is steel?

A
  • Alloys of iron that contain specific amounts of carbon and other metals
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20
Q

What are the properties of high carbon steel? + Use

A
  • Strong but brittle
  • Construction
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21
Q

What are the properties of low carbon steel? + Use

A
  • Softer and more easily shaped
  • Making car body panels as they are malleable
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22
Q

What metals do stainless steel contain and what are its properties?

Study These Flashcards
A
  • Chromium, nickel and iron
  • Hard and resistant to corrosion
23
Q

What is a use for stainless steel?

24
Q

How is soda lime glass made?

Study These Flashcards
A
  • Heating a mixture of sand, sodium carbonate and limestone
25
What is borosilicate glass made from?(2)
Sand and boron trioxide
26
How is borosilicate glass different from soda lime glass?
- Melts at higher temperatures than soda lime glass
27
What are examples of clay ceramics?(2)
- Pottery and bricks
28
How are clay ceramics made?(2)
- Shaping wet clay - Heating in a furnace
29
What do the properties of polymers depend on?(2)
- The monomers they are made from - Conditions under which they are made
30
What monomer is poly(ethene) made from?
Ethene
31
What are the properties and uses of low density polyethene? (LDPE)
- Flexible, unreactive, made into films - Used for carrier bags, bubble wrap
32
What are the properties and uses of high density polyethene(HDPE)?
- Strong, flexible, resists shattering, resists chemical attack - Used for plastic bottles, pipes, buckets
33
What is the structure of low density polyethene?
- Polymer chains are branched - Molecules are arranged randomly
34
What is the structure of high density polyethene?
- Less brancing of polymer chains - Molecules line up much more closely
35
What are thermosoftening polymers?(3)
- Polymers that melt when they are heated - Most plastics in everyday life - Can be recycled, involves melting them before making a new product
36
Why do thermosoftening plastics melt when heated?
- No covalent bonds between molecules - Intermolecular forces between the polymer chains which are very weak and are easily overcome when heated
37
What are thermosetting polymers? + Use (3)
- Polymers that do not melt when heated - Tend to char and burn when heated, resistant to higher temperatures - Used to make electrical plugs
38
Why do thermosetting polymers not melt when heated?
- Polymer chains have cross links between them - Cross linsk are very strong and so it would take a lot of energy to break these links to cause the polymer to melt
39
What is a composite?
- A material made up two materials with different properties - Have reinforcement - fibers or other material that make up the bulk - Have the matrix whcih binds the reinforcement together
40
What are 4 exampels of composites, their reinforcement and matrix?
- Reinforced concrete = r: steel, m: concrete - Fibreglass = r: glass fibres, m: polymer resin - Carbon fibre reinforced polymer = r: carbon fibres, m: polymer resin - Chipboard = r: wood chips, m: resin glue
41
Properties of the fibres in fibre glass and carbon fibre reinforced polymer?
- Fibres have a low density - Strong in tension, not easily stretched - Flexible
42
Properties of the polymer resin in fibre glass and carbon fibre reinforced polymer?
- Not strong but stiff
43
What is a natural composite material?
- Wood - reinforcement of cellulose fibres bonded together by a matrix of lignin - Fibres are aligned alongside each other so wood is stronger in one direction that in the other
44
What is the Haber process?
- Process used to manufacture ammonia - Reversible reaction
45
What are the raw materials for the harber process? What is the source for them?
- Nitrogen - from air - Hydrogen - from natural gas
46
What happens during the harber process?(5 steps)
1. Nitrogen(from air) and hydrogen(from natural gas) are pumped through pipes 2. Pressure of mixture of gases is increased to 200 atmospheres 3. Pressurised gases are heated to 450 degrees and passed through a tank containing an iron catalyst 4. The reaction mixture is cooled to ammonia liquefies and can be removed 5. Unreacted nitrogen and hydrogen are recycled
47
What is the word equation for the harber process?
Nitrogen + Hydrogen ⇌ Ammonia
48
What happens to ammonia produced and on cooling?
- Some of the ammonia produced breaks down into nitrogen and hydrogen - On cooling, the ammonia liquefies and is removed - The remaining hydrogen and nitrogen are recycled
49
Identify the catalyst in the harber process and explain why it is used
- Iron as catalyst - Used because it lowers the activation energy of the reaction - Relatively cheap and helps to achieve an acceptable yield of ammonia in an acceptable time
50
Identify and explain the temperature that the Harber process takes place at
- 450 degrees as an optimum - Breakdown of ammonia is an edothermic reaction so when temperatures are higher the breakdown of ammonia would increase - At lower temperatures the particles would move slower leading to fewer collisions between hydrogen and nitrogen and so less ammonia would form
51
Identify and explain the pressure that the Harber process takes place at
- 200 atmospheres as optimum - The greater the pressure the higher the yield of ammonia as equlibrium is moved to the right - The higher the pressure the higher the cost and the greater the safety risk
52
What 3 elements do NPK fertilisers contain?
- Nitrogen - Phosphorus - Potassium
53
What are NPK fertilisers?
Formulations of various salts

Chemistry P2 (8 decks)

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