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chemistry: paper 2 > using resources > Flashcards

using resources Flashcards

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1
Q

describe ceramics:
-how its made
-give examples

A

a group of hard, brittle, corrosion resistant, heat resistant materials

-made by shaping and then firing a nonmetallic material, such as clay, at a high temperature

-two main groups: glass and clay ceramics

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2
Q

properties of glass:

A

-transparent, hard, good thermal insulator

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3
Q

what is (soda lime) glass made out of?

A

-sodium carbonate
-limestone
-sand

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4
Q

what is a composite?

A

two or more materials with diff properties, combined to prod a material with more desirable properties

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5
Q

low density poly(ethene) (LDPE)
-conditions
-properties
-uses

A

-moderate temps, high pressure, catalyst

-more flexible but weaker

-carrier bags

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6
Q

high density poly(ethene) (HDPE)
-conditions
-properties
-uses

A

-low temps/pressure, catalyst

-more rigid but stronger

-drainpipes

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7
Q

what is a thermosoftening polymer?

A

-made from many polymer chains
-held together by weak intermollecular forces
-break easily when heated > polymer melts > can be moulded into a difff shape > will harden again when it cools

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8
Q

what is a thermosetting polymer?

A

-many poly chains
-strong covalent bonds
-lots of energy to break
-strong, hard, rigid

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9
Q

how to prevent iron from rusting:
(barrier methods)
-definition

A

to prevent O2 and H2O from touching the iron

-paint the surface
-oil or grease (moving parts)
-electroplating (using electrolysis to cover iron with thin metal to protect it)

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10
Q

how to prevent iron from rusting:
(sacrificial methods)
-definition

A

adding a more reactive metal to the iron

-other metal will react instead of iron

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11
Q

what is galvanizing?

A

mix of barrier and sacrificial

-iron covered in layer of zinc (barrier)
-if zinc gets scratched and iron exposed, then the zinc will still react with the oxygen bcs its so reactive (sacrificial)

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12
Q

4 main stages of life cycle assessment:

A
  1. extracting and processing raw materials
  2. manufacturing and packaging
  3. using
  4. disposing
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13
Q

purpose of LCA:

A

to assess environmental impacts of products

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14
Q

ways in which part 1 of LCA damages enviro:

A

-releases pollutants
-co2 emissions from energy use
-digging of mines
-destruction of habitats

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15
Q

what is potable water?

A

-water that is safe to drink

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16
Q

3 criteria to meet for potable water:

A

-low amount of dissolved substances
-pH betw 6.5 - 8.5
-no microorganisms

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17
Q

what is an aquifer:

A

permeable rock that traps water under the surface

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18
Q

fresh water treatment steps:

A

-use wire mesh to filter out big things (leaves, twigs etc.)
-pass through bed of sand (to filter out smaller particle)

-sterilize by:
either bubbling chlorine gas thru it
UV
exposing to ozone

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19
Q

what is desalination:

A

-extracting potable water from sea

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20
Q

steps of waste water treatment:

A

-screening (to remove big parts from the water)
-sedimentation (letting it sit for some time so the heavier materials will sink and form sludge at the bottom)
-two parts will be seperated

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21
Q

the two separated parts in sedimentation:

A

-effluent
-sludge (heavier)

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22
Q

what is the Haber process?

A

-industrial production of ammonia from hydrogen and nitrogen

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23
Q

approx. how much air made of nitrogen?

A

78%

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24
Q

how is the hydrogen used in Haber process made?

A

mainly from reacting methane (from natural gas) with steam to form h2 and co2

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25
Q

importance of haber process:

A

ammonia produced is used in nitrogen based fertilizers that is used to grow all the food

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26
Q

conditions needed in H process:

A

450 C and 200 atm

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27
Q

how to separate the unreacted N2 and H2 from ammonia:

A

pass mixture into a condenser
the gaseous ammonia has a higher boiling point so it will cool and liquidify and get collected the unreacted gases will recycle back

28
Q

three main elements for npk fertilisers:

A

nitrogen, phosphorus, potassium
NPK are a formulation of salts that have the required percentages of elements needed by the plants

29
Q

why is nitrogen important for plants?

A

because it is needed to make amino acids (proteins) - essential for growth

30
Q

treating phosphate rock with nitric acid:

A

-prod. phosphoric acid and calcium nitrate
-phos. acid contains phosphorus but can’t directly add this to plants, so neutralise it with ammonia
-this prods ammonium phosphate, can be used as fertiliser

31
Q

treating phosphate rock with sulfuric acid:

A

-prod calcium phosphate and calcium sulfate
(mixture known as single superphosphate
»>can now be used in fertiliser

32
Q

treating phosphate rock with phosphoric acid:

A

-prod. triple superphosphate >found in NPK

33
Q

suggest a source of potassium in an NPK:

A

-potassium chloride
-potassium sulfate

both mined from ground, can be used straight away

34
Q

ammonia reactions in a lab:

A

-dilute concentrations of ammonia and nitric acid > safe to work with

35
Q

ammonia reactions in industry:

A

ammonia used as a gas & nitric acid is concentrated > more dangerous, react. very exothermic > heat prod. has to be removed safely > heat used in later stages

36
Q

what is a formulation?

A

-mixture made of specific ratio of chemicals
-ensures product has required properties

37
Q

3 criterias of potable water

A

-amount of dissolved substances have to be fairly low
-no microorganisms
-pH betw 6.5 & 8.5

38
Q

what is surface water

A

bodies of water exposed at surface
-lakes
-reservoirs
-rivers

39
Q

what is ground water

A

-aquifers
areas of permeable rock under the ground that trap water

40
Q

disadvantages of surface water

A

when hot and sunny , can dry up

41
Q

treatment of water:

A

-pass through mesh to filter out all big things
-pass it through bed of sand and gravel to filter other smaller bits
-sterilise to kill harmful microbes
by bubbling chlorine gas thru it
or exposing it to ozone
or ultraviolet light

42
Q

what is reverse osmosis in desalination

A

-salty water passed thru a membrane
-only allows h2o to go through
-all ions and larger molecules get trapped
-pure distilled water

43
Q

What is the main drawback of using desalination to get potable water?

A

It requires a lot of energy, so is very expensive (and contributes to global warming)

43
Q

What is the main drawback of using desalination to get potable water?

A

It requires a lot of energy, so is very expensive (and contributes to global warming)

44
Q

what is a pure substance

A

a substance containing only one compound or element

45
Q

what is phytomining?

A

a way to extract copper from low-grade ores

-plants are grown in soil that contains copper
-plants harvested and burnt in a furnace
-copper from ash dissolved in acid
-solution electrolysed (or displaced using scrap iron) to extract copper

46
Q

describe bioleaching

A

-bacteria mixed with low grade ore
-bacteria carry out chem reactions and prods a solution called leachate
this contains copper compounds we want
-now you can extract metal from compound by displacing it
or by electrolysis

47
Q

advantages of both bioleaching and phytomining

A

-allows us to economically extract metal from low grade ores
important as earths metal sources limited
-does not involve digging, transport, and disposing like traditional mining

48
Q

what are particulates and how are they harmful

A

-solid particles of carbon (soot)

-if inhaled, can lead to respiratory problems
-can cause smog (dark clouds) that reflect sunlight back into space

49
Q

what is global dimming

A

-when less light reaches the earth because of smog

50
Q

dangers of carbon monoxide

A

-if we breathe CO in, it can diffuse into the blood and bind to haemoglobin where oxygen was supposed to be
-less oxygen transported around body
-can lead to fainting, coma, death

51
Q

CO is both …… and …… .

A

colorless & odourless

52
Q

Explain how a catalyst increases the rate of a reaction.

A

catalysts provide an alternate reaction pathway that has a lower activation energy

53
Q

Explain why carbon dioxide emissions during use and operation are not the total
carbon footprint for a car.
Refer to the stages of the life cycle assessment of a car in your answer.
[3 marks]

A
  • (because carbon dioxide is
    emitted in) extracting /
    processing raw materials
  • (and) manufacturing
  • (and) disposal at the end of its
    useful life
54
Q

why are very high pressures not used in Haber process

A
  • the energy costs would be high(er)
  • the equipment would need to be strong(er)
  • high(er) pressures are (more) dangerous
55
Q

how to make soda lime glass

A

mix together sand, sodium carbonate and limestone
- heat mix in a furnace till it melts

56
Q

problem w/ soda lime glass

A
  • low m.p.
    limits its use

-borosilicate glass has higher m.p., useful for objects that require heating

57
Q

how is borosilicate glass made

A

-melting a mixture of sand and boron trioxide

58
Q

Difference between thermosetting and thermosoftening polymers.

A
  • Thermosoftening polymers have weak intermolecular forces between the layers, they can be melted
  • Thermosetting polymers have strong crosslinks between the layers. So they can’t be melted.
59
Q

NPK fertilisers are formulations of diff..

A

salts
-these salts contain the required elements in percentages needed by plants

60
Q

how to obtain hydrogen for the haber process

A

by reacting methane w/ steam to form H & co2

61
Q

why is the haber process well suited for industrial productions

A

reactants are too difficult or expensive to obtain

62
Q

describe the haber process

A

-purified gases passed over a catalyst of iron at high temp (about 450°C) and high pressure (about 200 atmospheres).
-some of the hydrogen and nitrogen reacts to form ammonia. reaction is reversible so some of the ammonia produced breaks down into nitrogen and hydrogen:
nitrogen + hydrogen <-> ammonia

ammonia prod is a gas, but on cooling, the ammonia liquefies and is removed (to inc. yield). The remaining hydrogen and nitrogen are recycled.

63
Q

how to obtain phosphate for npk

A

-phosphate rock mined from underground
-has to be chemically processed b4 used in fertiliser

64
Q

how to obtain phosphate for NPK

A

-phosphate rock mined from underground
-has to be chemically processed b4 used in fertiliser

65
Q

what is the pressure and temperature compromise for haber process

A
  • 450 ‘ C
  • 200 atm

chemistry: paper 2 (6 decks)

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