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Chemistry Paper 2 > Using Our Resources > Flashcards

Using Our Resources Flashcards

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1
Q

Corrosion

A

Caused by chemical reactions between metal and substance in environment
Affect strength and appearance
Form of rusting

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2
Q

What is needed for rusting?

A

Both air and water for iron to rust

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3
Q

Preventing rusting

A 
Paint
Oil or grease
Plastic
Less reactive metal
More reactive metal
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4
Q

Zinc in rusting

A 
Protects iron
Iron is galvanised
Zinc is more reactive than iron
Zinc has stronger tendency to form positive ions by giving away electrojs
Zinc loses electrons = oxidised
Zinc is sacrificed to protect iron
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5
Q

Magnesium or aluminium in rusting

A

Used instead of zinc in harsher conditions

Usually if in contact with sea water

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6
Q

What’s an alloy?

A

Mixture of metals

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7
Q

Copper alloys

A 
Bronze = tine and copper = statues
Brass = zinc and copper = Hard and workable
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8
Q

Aluminium alloys

A

Low density
Alloyed with side range of other elements
Lightweight
Armour plating on tanks

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9
Q

Gold alloys

A

Harder when alloyed
Gold usually alloyed with copper
Jewellery
Varying proportions of 2 metals gives different shades

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10
Q

Steels

A

Iron and carbon

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11
Q

Carbon steels

A

Removing most carbon from iron = using blast furnace
Carbon content decreases = cheapest steels made
High carbon = strong and brittle
Low carbon = soft and easily shaped, not as strong and less likely to shatter

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12
Q

Alloy Steels

A

Steels = expensive, contain high percentage of metals
Nickel steel alloys = bridges, resistant to stretching, operates well under hot conditions
Chromium-nickel steels = stainless steel, hard, strong, resistant to corrosion, cooking utensils and cutlery
Stainless steels = chemical industry, make vessels, expensive, withstand high temperatures and pressures

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13
Q

What do the properties of polymers depend on?

A

Monomers used to make it

Conditions chosen to carry out reaction

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14
Q

What are the 2 types of polyethenes

A

HD and LD

high density and low density

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15
Q

LD polyethene

A

Very pressures and trace of oxygen, ethene forms LD polyethene
Polymer chains randomly branched and cannot pack closely together = so have low density

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16
Q

HD polyethene

A 
Using catalyst at 50*C and raised pressure
Makes straighter polyethene chains
Pack closely together
High density
High softening temperature
Stronger than LD
17
Q

How do you classify polymers?

A

What happens to them when they are heated

18
Q

Thermosoftening Polymers

A

Soften easily
Re-set when cool down
Made up of individual polymer chains that are tangled together

19
Q

Thermosetting Polymers

A

Do not melt when heated

Strong covalent bonds which form “cross inks” between chains

20
Q

Thermosoftening Chains forces

A 
Weal forces between chains
Heat = weak intermolecular forces broken
Polymer becomes soft
Polymer cools down = intermolecular forces bring polymer molecules back together
Polymer remoulded
21
Q

Thermosetting chains for forces

A

Monomers make covalent bonds between polymer chains
When heated to shape them
Bonds strong so stop polymer softening
Covalent “cross-links” between chains do not allow them to separate
Polymer char’s at high temperatures

22
Q

Glass

A 
Sand, limestone, sodium carbonate
Raw materials heated to 1500*C
Metals react to form molten glass
Cools down turns solid
Particles don't form regular pattern
Molten glass frozen
OR use glass making mixture
23
Q

Ceramics

A

Electrical insulators, resistant to chemical attack
Made by moulding wet clay into desires shaped then heating
Clay contain compounds of metals and non-metals = ionic bonding and covalent
Ions and atoms arranged in giant structures
Clay is wet, water molecules get between layers fired
Water driven out and strong bonds form = changing properties
High temp makes it hard
Brittle because when hit ions repel each other away, cracking

24
Q

Examples of composites

A 
Wood = plywood, thin sheets of wood glues together, plywood resists splitting along grain (MDF) made of woodchips, shavings or sawdust
Concrete = cement, sand and gravel mixed with water, hard, strong, resist bending
25
Q

Nitrogen-based Fertilisers

A

Plants need nitrogen = make proteins -> growth
Natural cycle of nitrogen = disturbed by farming crops
Crops plants grow = take in nitrate ions in soil
Need fertiliser to replace nitrogen and other nutrients taken by plant
Air has nitrogen = nitrogen is soluble in water, most plants only absorb soluble form of nitrogen

26
Q

What does the Haber Process do?

A

Turns nitrogen in air into ammonia

27
Q

Ammonia’s production from raw materials

A

Nitrogen from air

Hydrogen from natural gas

28
Q

How ammonia is mde

A

Nitrogen and hydrogen purified
Passed over an iron catalyst at high temperature
Ammonia removed by cooling the gases so ammonia liquifies
Unreacted nitrogen and hydrogen gases are recycled back into reaction mixture. Then re-compressed and heated

29
Q

What is the reaction like in the haber process?

A

Reversible

30
Q

Effect of pressure on the Haber Process

A

N2 + 3H2 <=> 2NH3
4 molecules on left side
2 molecules on right
Volume of reactants is greater than volume of products
Increase in pressure shifts equilibrium to right, producing more ammonia
Maximum yield = as much pressure as possible -> lots of energy, expensive
Lower yield = reduces costs, produces reasonable rates of reaction

31
Q

Effect of temperature on the Haber process

A

Lowering temp = increase amount of ammonia, slow gas molecules, less collision and less energetic, reduces effectiveness of iron catalyst
High temp = get reaction going at reasonable rate, reduces yield of ammonia

32
Q

Effect of a catalyst on the Haber process

A

Speed up reaction of both forward and reverse reaction
Does not affect yield of ammonia
Causes ammonia to be produced more quickly

33
Q

Ammonia and fertilisers

A

Ammonia = fertiliser
Most ammonia changes into compounds
Other fertilisers = salts by ammonia + acid => salt
Neutralisation reaction = ammonia + phosphoric acid (acid + alkali)

34
Q

Making NPK fertilisers in industry

A

Crops need phosphorus
Phosphorus mined from ground cannot be used on soil = insoluble in water, rock treated with acids to make fertiliser salts

35
Q

How is phosphorus rock treated?

A

With nitric acid = phosphoric acid + calcium nitrate => ammonium phosphate
With sulfuric acid = calcium phosphate + calcium sulfate => single superphosphate
With phosphoric acid = calcium phosphate => triple superphosphate

Chemistry Paper 2 (9 decks)

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