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chemistry: paper 2 > using resources > Flashcards

using resources Flashcards

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
importance of haber process:
ammonia produced is used in nitrogen based fertilizers that is used to grow all the food
26
conditions needed in H process:
450 C and 200 atm
27
how to separate the unreacted N2 and H2 from ammonia:
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
three main elements for npk fertilisers:
nitrogen, phosphorus, potassium NPK are a formulation of salts that have the required percentages of elements needed by the plants
29
why is nitrogen important for plants?
because it is needed to make amino acids (proteins) - essential for growth
30
treating phosphate rock with nitric acid:
-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
treating phosphate rock with sulfuric acid:
-prod calcium phosphate and calcium sulfate (mixture known as single superphosphate >>>can now be used in fertiliser
32
treating phosphate rock with phosphoric acid:
-prod. triple superphosphate >found in NPK
33
suggest a source of potassium in an NPK:
-potassium chloride -potassium sulfate both mined from ground, can be used straight away
34
ammonia reactions in a lab:
-dilute concentrations of ammonia and nitric acid > safe to work with
35
ammonia reactions in industry:
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
what is a formulation?
-mixture made of specific ratio of chemicals -ensures product has required properties
37
3 criterias of potable water
-amount of dissolved substances have to be fairly low -no microorganisms -pH betw 6.5 & 8.5
38
what is surface water
bodies of water exposed at surface -lakes -reservoirs -rivers
39
what is ground water
-aquifers areas of permeable rock under the ground that trap water
40
disadvantages of surface water
when hot and sunny , can dry up
41
treatment of water:
-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
what is reverse osmosis in desalination
-salty water passed thru a membrane -only allows h2o to go through -all ions and larger molecules get trapped -pure distilled water
43
What is the main drawback of using desalination to get potable water?
It requires a lot of energy, so is very expensive (and contributes to global warming)
43
What is the main drawback of using desalination to get potable water?
It requires a lot of energy, so is very expensive (and contributes to global warming)
44
what is a pure substance
a substance containing only one compound or element
45
what is phytomining?
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
describe bioleaching
-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
advantages of both bioleaching and phytomining
-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
what are particulates and how are they harmful
-solid particles of carbon (soot) -if inhaled, can lead to respiratory problems -can cause smog (dark clouds) that reflect sunlight back into space
49
what is global dimming
-when less light reaches the earth because of smog
50
dangers of carbon monoxide
-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
CO is both ...... and ...... .
colorless & odourless
52
Explain how a catalyst increases the rate of a reaction.
catalysts provide an alternate reaction pathway that has a lower activation energy
53
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]
- (because carbon dioxide is emitted in) extracting / processing raw materials - (and) manufacturing - (and) disposal at the end of its useful life
54
why are very high pressures not used in Haber process
* the energy costs would be high(er) * the equipment would need to be strong(er) * high(er) pressures are (more) dangerous
55
how to make soda lime glass
mix together sand, sodium carbonate and limestone - heat mix in a furnace till it melts
56
problem w/ soda lime glass
- low m.p. limits its use -borosilicate glass has higher m.p., useful for objects that require heating
57
how is borosilicate glass made
-melting a mixture of sand and boron trioxide
58
Difference between thermosetting and thermosoftening polymers.
- 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
NPK fertilisers are formulations of diff..
salts -these salts contain the required elements in percentages needed by plants
60
how to obtain hydrogen for the haber process
by reacting methane w/ steam to form H & co2
61
why is the haber process well suited for industrial productions
reactants are too difficult or expensive to obtain
62
describe the haber process
-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
how to obtain phosphate for npk
-phosphate rock mined from underground -has to be chemically processed b4 used in fertiliser
64
how to obtain phosphate for NPK
-phosphate rock mined from underground -has to be chemically processed b4 used in fertiliser
65
what is the pressure and temperature compromise for haber process
- 450 ' C - 200 atm

chemistry: paper 2 (6 decks)

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