Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry Mocks > C6.1 > Flashcards

C6.1 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

What are the essential elements (needed for plant growth)?

A

Nitrogen, phosphorus and Potassium : NPK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Symptoms of mineral deficiency of Nitrogen

A

Poor growth, yellow leaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Symptoms of mineral deficiency of Phosphorus

A

Poor root growth, discoloured leaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Symptoms of mineral deficiency of Potassium

A

Poor fruit growth, discoloured leaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are fertilisers?

A

Fertilisers are substances that replace the elements used by plants as they grow - they provide them in a water soluble form so that the plant roots can absorb them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Water soluble forms of NPK?

A

Nitrogen in Nitrate ions NO3-, ammonium ions NH4+
Phosphate ions PO4(3)-
Potassium ions K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the Haber Process?

A

Process which manufactures ammonia from nitrogen and hydrogen:
N2 (g) + 3H2 (g) ->

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is the Haber Process carried out?

A

Raw materials needed are :
Air - Nitrogen is manufactured by fractional distillation of liquefied air
Natural gas (methane) and steam - they react together to form hydrogen
Purified hydrogen and nitrogen pass through compressor and iron catalyst - high pressure (maximise yield) and then after reaction vessel it passes through condenser and produces liquid ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens in a fertiliser factory?

A

Variety of raw materials are needed including sulfur and phosphate rock (as well as potassium chloride to make potassium nitrate) to produce sulfuric acid and phosphoric acid ; range of fertilisers can be made
Ammonium nitrate/sulfate - NH4NO3/(NH4)2SO4
Ammonium phosphate - (NH4)3PO4
Potassium nitrate - KNO3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How to make potassium sulfate in the Laboratory?

A

1) Dilute KOH (aq) in conical flask -> add phenolphthalein indicator (enables you to determine when alkali has been neutralised at end point)
2) Add dilute H2SO4 (aq) from burette -> stop at end point when indicator changes from pink to colourless
3) Add activated charcoal which attracts phenolphthalein and then filter the mixture to remove charcoal with phenolphthalein attached to it
4) Warm the filtrate to evaporate the water leaving potassium sulfate behind (do not heat this to dryness)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How to make ammonium sulfate in the laboratory?

A

1) Place the dilute ammonia NH3(aq) solution in conical flask with methyl orange indicator -> releases ammonia in gas state which has irritating sharp smell (avoid breathing it in)
2) Add dilute H2SO4 (aq) from burette -> stop when indicator changes from yellow to red
3) When you reach end point add extra ammonia solution to ensure reaction is complete - any remaining ammonia will be lost during evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Hazards of making fertilisers in the lab?

A

Ammonia and potassium hydroxide are alkaline - ammonia produces an irritating sharp smell and excess ammonia given off in gas state when warmed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are industrial process different from laboratory ones?

A

In laboratory it is a batch process (make small amounts at one time)
Industrial process it is continuous - large amounts and go on all the time
In laboratory - start with pure substance bought from a chemical manufacturer
Factors start with raw materials which must be purified before use - substances obtained from the ground, air or sea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Comparison of batch and continuous processes

A

Rate of production - batch low, continuous high
Cost of equipment - batch low, continuous high
Number of workers - batch large, continuous small
Ease of automation - batch low, continuous high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Conditions for Haber Process

A 
N2 (g) + 3H2 (g) -> 2NH3 (g)
Conditions : 
Pressure of 200 atmospheres
Temperature of 450
Iron catalyst
Results in an equilibrium yield of about 30%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Factors determining pressure compromise of Haber Process

A

Balanced equation means increasing pressure moves equilibrium yield to product side with least moles increasing yield
HOWEVER would be too hazardous and expensive to choose a very high pressure and the equilibrium yield does not justify these additional costs resulting in compromise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Factors determining temperature of Haber Process

A

Forward reaction of Haber Process is exothermic therefore if temperature increases equilibrium yield favours backward reaction and not forward ; therefore lower temperature results in higher equilibrium yield
BUT cannot be too low as need to be able to achieve a reasonable rate of reaction and iron catalyst only works efficiently ABOVE 400

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Helpful conditions in process itself?

A

Allows unreacted nitrogen and hydrogen to be recycled improving overall yield to around 97%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Stage 1 of Producing Sulfuric Acid

A

Sulfur combusts in air to produce sulfur dioxide (exothermic)
S (s) + O2 (g) -> SO2 (g)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Stage 2 of producing Sulfuric Acid

A

Stage 2 is the CONTACT PROCESS
Sulfur dioxide and Oxygen react to produce Sulfur Trioxide
2SO2 (g) + O2 (g) ->

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Pressure compromise for contact process

A

3 moles on the left and 2 on the right - therefore if pressure is increased equilibrium position moves to the right and yield do sulfur trioxide increases
But equilibrium position is already far to the right therefore no need for high pressures and 2 atmospheres is enough (200000 Pa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Temperature compromise for contact process

A

Forward reaction is exo therefore backwards reaction is endo - if temperature increases equilibrium position moves to the left and yield of sulfur trioxide decrease therefore low temperature = high yield
Temperature is 450 degrees as Vanadium Oxide V2O5 catalyst only works above 380 and to produce reasonable rate of reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Stage 3 of producing Sulfuric acid

A

Carried out in two steps because highly exothermic and would produce hazardous acidic mist
Step 1 : Sulfur trioxide passed through Sulfuric acid to make oleum
H2SO4 (l) + SO3 (g) -> H2S2O7 (l)
Step 2 : Oleum added to water makes large volume of H2SO4
H2S2O7 (l) + H2O (l) -> 2H2SO4 (aq)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How is alcohol made from renewable raw materials?

A

Renewable raw materials are constantly being replaced as they are used up - shoul not run out
Ethanol is made from plant sugars using fermentation ; process relies on fungi called Yeast which contains enzymes that catalyse reaction of glucose into carbon dioxide and ethanol
C6H12O6 (aq) -> 2CO2 (g) + 2C2H5OH (aq)
Can carry out fermentation as a school batch process - simple apparatus
Fermentation carried out at 35 degrees and RTP BECAUSE
If temperature too high then enzymes denatured
If temperature too low yeast cells become inactive
Industrial fermentation uses same conditions but more complex equipment
Laboratory - conical flask with glucose and yeast with connecting glass tube to test tube of limewater (produces CO2 which makes limewater milky)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is alcohol made from non-renewable raw materials?

A

Non renewable materials are used faster than they can be replaced and therefore are finite and will run out eventually
Ethane can be obtained from crude oil which is non renewable
Ethanol can be produced by the hydration of ethene
Ethene + steam ->

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Comparison of hydration of ethene and fermentation of sugars
F - fermentation of sugars
H - hydration of ethene

A

Cost of raw materials : F - low / H - high
Conditions : F - moderate temperature and normal pressure / H - high temp and high pressure
Energy requirements : F - low / H - high
Rate of reaction : F - low / H - high
Percentage yield : F - low (15%) / H - high (95%)
Purity of product : F - low (needs filtering and fractional distillation) / H - high (no by products)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is an ore?

A

An ore is a rock or mineral that contains enough metal to make it economical to extract the metal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Different ores and the metal compounds they contain

A

Malachite ore - copper carbonate
Bauxite ore - aluminium oxide
Haematite - iron (iii) oxide

29
Q

What extraction methods are there?

A

All metals could be extracted using electrolysis BUT electricity is expensive AND IF METAL IS LESS REACTIVE THAN CARBON THEN CHEAPER METHODS CAN BE USED SUCH AS HEATING THEIR COMPOUNDS WITH CARBON OR CARBON MONOXIDE
Copper silver gold platinum zinc iron tin lead (all less reactive than carbon)

30
Q

How is copper extracted?

A

Copper is extracted from copper sulfide - CuS
Stage 1 : Copper sulfide + oxygen -> copper (ii) oxide + sulfur dioxide
2CUS (s) + 3O2 (g) -> 2CuO (s) + 2SO2 (g)
Stage 2 : The copper(ii) oxide is heated with carbon
Copper (ii) oxide + carbon -> copper + carbon dioxide
2CuO(s) + C(s) -> 2Cu (s) + CO2 (g)
REDOX
Copper oxide is reduced as it loses oxygen
Carbon is oxidised as it gains oxygen
Carbon is the reducing agent - takes oxygen from copper oxide reducing it in the process
Copper (ii) oxide can also be reduced to copper by heating it with methane or with hydrogen

31
Q

Extracting copper with charcoal - laboratory experiment

A

1) Mix two powders in a crucible with lids on to stop powders escaping during heating and to stop air getting in for carbon to combust
2) Heat it strongly and after several minutes allow crucible to cool
3) Transfer contents to beaker of water where copper sinks to bottom and excess charcoal suspends in the water
4) Wash copper to separate it
Excess charcoal powder is used to ensure that all of the copper (ii) oxide is reduced to copper and eye protection should be worn throughout this practical.
Charcoal is mainly carbon

32
Q

What is a blast furnace?

A

Iron is extracted from its ore using a large reaction container called a blast furnace - industrial reaction vessel for iron production

33
Q

What raw materials are added to the blast furnace to produce iron?

A

Haematite iron ore which produces iron(iii) oxide
Coke- mostly carbon and produced by heating coal (incomplete combustion)
Limestone - used to purify iron
Hot air is forced into bottom of blast furnace

34
Q

Reactions in blast furnace

A

Carbon monoxide is main reducing agent in the blast furnace - formed when coke reacts with CO2
Stage 1 - coke burns in hot air to make CO2
C(s) + O2 (g) -> CO2 (g)
Stage 2 - more coke reduces CO2 to make CO
C (s) + CO2 (g) -> 2CO (g)
Stage 3 - CO reduces iron(iii) oxide to iron at high temperatures
3CO (g) + Fe2O3 (s) -> 3CO2 (g) + 2Fe (l)

35
Q

Processes in blast furnace after iron oxide is reduced to form iron

A

Molten iron (liquid) contains Sandy impurities from iron ore therefore purified through limestone (calcium carbonate)
Stage 1 - Calcium carbonate decomposes in the high temperatures
CaCO3 (s) -> CaO (s) + CO2 (g)
Stage 2 - Calcium oxide formed reacts with silica from Sandy impurities to form calcium silicate (slag - which floats on top of molten iron and is then removed)
CaO (s) + SiO2 (g) -> CaSiO3 (l)

36
Q

Aluminium properties

A

Exists naturally as aluminium oxide Al2O3 found in ore called bauxite - MORE REACTIVE THAN CARBON THEREFORE MUST BE EXTRACTED THROUGH ELECTROLYSIS (unlike iron/copper) but electrolysis only works if compound is in solution or if it is molten but aluminium oxide does not dissolve in water and its melting point is very high

37
Q

How is aluminium oxide electrolysed?

A

Melting point too high therefore will be too expensive - instead it is dissolved in molten cryolite and cryolite has a much lower melting point than aluminium oxide allowing electrolysis to occur at a much lower temperature
Molten mixture is contained in huge electrolysis cell (made from steel lined with graphite) - graphite lining acts as the cathode (negative electrode) and large graphite blocks act as anodes (positive electrodes)

38
Q

Aluminium oxide (+ molten cryolite) electrolysis

A 
Aluminium is produced at the cathode
Oxygen is produced at the anodes
Oxygen reacts with hot graphite anodes producing carbon dioxide - so anodes gradually burn away meaning they must be replaced frequently (adds to cost of producing aluminium)
Cathode - Al3+ + 3e- -> Al
Anode - 2O2- -> O2 + 4e-
39
Q

What is acid mine drainage?

A

Mines often flood when they are abandoned - metal sulfides oxidise underwater producing sulfuric acid which reacts with other metal ores and this forms soluble metal compounds leaving with water as it drains from mine ; happens naturally but reaction catalysed by certain bacteria (basis of bioleaching)

40
Q

What is bioleaching?

A

Bacteria oxidise iron(ii) and sulfide ions to transfer energy - sulfuric acid forms in the presence of water and oxygen and this breaks down copper sulfide ores releasing copper ions

41
Q

Bioleaching advantages

A

It is cheaper than traditional mining methods
Allows metals to be extracted from ores that contain too little metal for traditional methods to be profitable (low grade ores)
Bacteria occur naturally and no special treatment needed
No sulfur dioxide produced in atmosphere
BUT IT IS VERY SLOW and toxic substances are sometimes produced
Measures put into place to avoid sulfuric acid from escaping into water supplies and the soil

42
Q

What is photo extraction?

A

Plants absorb dissolve ions through their roots and these accumulate in their roots shoots and leaves
In photo extraction a crop is planted in soil containing a low-grade ore or mine waste - a complexing agent may be added so the plants can absorb the metal ions more easily and the plants are then harvested and burnt to ash with a high concentration of the metal
Metal can be extracted just as if the ash was a high grade ore (smelted to yield metal)

43
Q

Advantages of phytoextraction

A

Cheaper than traditional mining
Produces less waste
BUT IS SLOW
Crops may need replanting and harvesting for several years before the available metal is removed from the soil
Closer to being carbon neutral - sustainable
Burning plants produce CO2 but they absorb CO2 for photosynthesis as they grow

44
Q

What are alloys?

A

Alloys are a mixture of two or more elements with at least one of which is a metal

45
Q

Types of alloys

A

Steel - iron - building bridges/cars
Duralumin - aluminium and copper - aircraft parts
Solder - tin and copper - joining electrical components/copper pipes
Brass - copper and zinc - musical instruments
Bronze - copper and tin - bells

46
Q

What is solder like?

A

Made of tin and copper and melts at 227 - useful for joining electrical components without damaging them and hot solder in the liquid state flows into the gap between them solidifying quickly
Metals are good conductors of electricity so the soldered joint allows an electric current to pass

47
Q

What are brass and bronze like?

A

Layers of metal atoms slide over one another when metals are stretched or bent - alloys are often stronger and harder than individual metals they contain
Brass contains copper and zinc of different size making it more difficult for copper atoms to slide over one another (distortion)
Brass is stronger and resists corrosion - does not react easily with air or water so makes it useful for making the pins for electrical plugs
Bronze also resists corrosion and is stronger and harder than copper - useful for making propellers for ships and used to make bells
Molten bronze expands slightly while it solidifies so fills tiny details in an artist’s mould

48
Q

What is corrosion?

A

The reaction of a metal with substances in its surroundings such as air or water

49
Q

Difference between corrosion and rusting?

A

When iron and steel corrode it is called rusting else any other metals is just corrosion - only very unreactive metals such as gold and platinum do not corrode

50
Q

What happens when objects rust?

A

Rusting is a redox reaction - iron is oxidised to hydrated iron(iii) oxide when it reacts with oxygen and water ; this is the familiar orange-brown rust you see and it easily flakes off the surface of the object exposing fresh metal underneath

51
Q

Investigating rusting

A

3 boiling tubes should be set up

1) Steel nail contains anhydrous calcium chloride - absorbs water vapour keeping it dry
2) Boiled water containing no dissolved oxygen - and a bung with no air getting back in
3) Nail exposed to air and water

52
Q

How does silver corrode?

A

Corrodes in the presence of hydrogen - H2S and the hydrogen sulfide reacts with silver when oxygen and water are also present corroding the silver and producing a thin layer of black silver sulfide Ag2S (turns them black)

53
Q

Ways to reduce rusting?

A

Prevent air and water reaching the surface of the metal - painting/plating with zinc (galvanising)/plating with tin
If paint is damaged then rusting starts on the exposed metal continuing underneath the paint and it eventually flakes off exposing fresh metal to air and water

54
Q

What is sacrificial protection?

A

Involves coating a metal that is more reactive than the one underneath (usually iron) such as magnesium/zinc - the more reactive metal corrodes first and sacrifices itself to protect the iron or steel underneath and this useful when painting is difficult ; ships have zinc or magnesium blocks bolted onto their hull below the waterline to protect the hull form rusting and gradually corrode away - have to be replaced

55
Q

How does sacrificial protection work?

A

Iron atoms lose electrons to form iron(iii) ions
Fe -> Fe3+ + 3e-
More reactive the metal more easily it loses electrons and sacrificial metals like zinc and magnesium lose electrons more easily than iron does (more readily oxidised than iron)

56
Q

How does metal plating work?

A

Prevents air and water reaching the iron or steel below
Galvanising involves dipping the metal object in molten zinc -
1) Stops air and water reaching the iron steel below
2) Acts as a sacrificial metal so that the object is protected even if zinc layer is damaged
Tin plating - electroplating steel object with run however tin is les reactive than iron so if tin layer is damaged the steel acts as a sacrificial metal for the tin and rusts even faster than normal

57
Q

Properties of ceramics

A 
Hard non metallic materials like brick/glass/porcelain - contain metals and non metals combined to form giant ionic lattices
High melting points
Hard and stiff but brittle
Poor conductors of electricity and heat
Unreactive as they are oxides
58
Q

Factors for choosing a material for electrical cable

A

Good conductor of electricity
Lightweight and strong - does not stretch/snap easily
Resist corrosion
Aluminium is a good conductor and less dense so it is usually chosen
Copper has low tensile strength but good conductivity
Steel is very dense and has high tensile strength (low conductivity)

59
Q

Factors for choosing material for insulators

A

CERAMICS - poor conductors of electricity
Glads has an irregular giant structure without crystals and usually transparent
Other ceramics are glazed and have many crystals (hard waterproof surface)

60
Q

What are composite materials?

A

Two or more materials combined together each with different properties - properties of composite material are different from those of the materials it contains
Clothes are composite to be lightweight and comfortable to wear
Many composite materials consist of fibres embedded in a polymer resin - low density and high tensile strength but are brittle whereas the resin is hardwearing but is not strong ; lightweight, strong and hard ; example includes fibreglass which consist of glass fibres in a resin and used for canoes
Carbon fibres consist of carbon fibres in a resin - more expensive than fibreglass

61
Q

How are composites used in buildings?

A

Concrete is a composite that consist of aggregate sand and cement - when water is added reaction occurs to bind the ingredients together and concrete has a high compressive strength meaning that it resist being squashed - useful for foundations but low TENSILE STRENGTH (cracks easily under heavy weights)
Steel has high tensile strength so by embedding steel into concrete as it sets create steel reinforced concrete which has high compressive and high tensile strength

62
Q

Wood composite materials?

A

Wood consists of long fibres laying side by side naturally to make a grain - stronger along the grain than across the grain and plywood is a composite material in which the thin sheet of wood are glued together in layers - grain set at right angles to layer below creating a composite material that resists bending in both directions (useful for floors and walls)

63
Q

How are properties and uses related?

A

Consider more than one property before deciding use

Cost/tensile strength/melting point/maximum temperature

64
Q

What is a life cycle assessment?

A

LCA is a cradle to grave analysis on the impact of making using and disposing of a manufactured product
Sustainability - raw materials and energy
Environmental impact
Lifespan of product
Disposal

65
Q

Uses of LCA data

A

Identify stages that could be improved - energy usage at different stages

66
Q

Why should you recycle materials?

A

Disposal in landfill sites is not an efficient use of resources- recycling is important because it
Conserves limited raw materials and energy resources
Reduces release of harmful substances into the environment
Reduces waste

67
Q

Factors affecting recyclability

A

How easily the waste can be collected and sorted
Amount and type of any by-products released by recycling
Cost of recycling compared to disposal/incineration
Amount of energy involved

68
Q

How are materials recycled

A

Collected and transported to a recycling plant
Materials are sorted
Glass is not contaminated by metal
Shredded/crushed into smaller pieces
Metals are melted by heating and poured into new blocks called ingots/paper is mixed with water, cleaned, rolled, heated to create new paper/glass is melted and moulded into new glass objects/polymers are me,ted and formed into new objects

Chemistry Mocks (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions