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chemistry > C6 > Flashcards

C6 Flashcards

(111 cards)

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1
Q

what is a metal ore?

A

a rock which contains enough metal to make it economical to extract the metal

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2
Q

how can a metal be extracted from it’s ore?

A

by reduction (using carbon) or by electrolysis (splitting with electricity)

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3
Q

what do some ores may have to be before metal is extracted?

A

concentrated- getting rid of unwanted rocky material

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4
Q

what are two other ways to extract metals from their ores?

A

-biological methods
-displacement reactions

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5
Q

when an ore is reduced what happens?

A

oxygen in removed from it

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6
Q

how does the position of the metal in the reactivity series effect reduction?

A

it determines whether it can be reduced with carbon

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7
Q

metals higher than carbon in the reactivity series…

A

can be extracted using electrolysis

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8
Q

metals below carbon in the reactivity series

A

can be extracted by reduction using carbon

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9
Q

what is the reactivity series order?

A

potassium
sodium
calcium
magnesium
aluminium
carbon
zinc
iron
tin
lead
hydrogen
copper
silver
gold
platinum

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10
Q

what is reduction?

A

removal of oxygen from a compound

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11
Q

what is displacement?

A

a reaction where a more reactive metal removes a less reactive metal from it’s compound

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12
Q

what state does a metal have to be in before it is extracted using electrolysis?

A

it has to be molten

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13
Q

what is the main difference in electrolysis and reduction with carbon?

A

electrolysis is expensive as it uses electricity

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14
Q

what is smelting?

A

an ore being heated in a furnace

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15
Q

what are two pure unreactive metals?

A

silver and gold

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16
Q

why is it better to extract copper using electrolysis?

A

smelting produces copper which is impure- it won’t conduct electricity.

copper is often used in electrical wiring- which makes it not useful.

electrolysis is used to purify it even if it is expensive.

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17
Q

what are low grade ores?

A

ores that only contain a small amount of metal in them

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18
Q

what are two biological methods of extraction?

A

bioleaching
phytoextraction

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19
Q

what is bioleaching?

A

use of bacteria to separate metals from their ores. the bacteria get energy from the bonds between the atoms in the ore which separate the metal from the ore.

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20
Q

what is phytoextraction?

A

growing plants in soil that contains metal compounds. the plants cant use or get rid of the metals so they gradually build up in the leaves. the plants are then harvested, dried and burned in a furnace

the only problem with this is that plants take a while to grow

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21
Q

what is a life cycle assessment?

A

an assessment that looks at each stage of the life of a product- it shows the potential environmental impact at each stage

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22
Q

what is in a life cycle assessment?

A

-use of sustainable raw materials
-use of energy at all stages
-use of water at all stages
-production and disposal

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23
Q

what could you consider when choosing raw materials?

A

-metals have to be mined and extracted from their ores- needs lots of energy which causes pollution

-raw materials for chemical manufacture often come from crude oil:
- finite resource
- getting crude oil and refining requires a lot of energy and causes pollution

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24
Q

what should you consider when assessing manufacture of a product?

A

-use of energy
-pollution (harmful gases)
-waste products and how to dispose of them
-use of water in chemical manufacture and water pollution

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25
what can some waste be turned into?
other useful chemicals which reduces the amount that ends up polluting the environment
26
what can you consider when assessing product use?
-if gives off toxic fumes -fertilisers can leak into water sources and cause damage to eco systems -burning fuels releases greenhouse gases
27
what should you consider when assessing disposal of a product?
-landfill waste can pollute water and land and products in landfill may be burnt which causes air pollution
28
what does burning fossil fuels cause?
acid range and climate change
29
why is recycling a good option?
-recycled materials use little energy needed to extract and refine the material -it saves money -recycling cuts down on waste sent to landfill- decreases pollution
30
why might recycling be complex?
-you need energy to reprocess the materials into new forms -items will often need sorting into different catagories -you need to compare how much energy is used for recycling vs disposing
31
what is crude oil formed from?
buried remains of plants and animals
32
what is a hydrocarbon?
a compound that contains carbon and hydrogen only
33
what is viscosity?
how thick a substance is
34
what is flamability?
ability to ignite something
35
what is crude oil mostly used for?
used as a raw material to create lots of petrochemicals- petrol or natural gas
36
what is crude oil a mixture of?
lots of different length hydrocarbons
37
how are the different compounds in crude oil separated?
by fractional distillation
38
what is the process of fractional distillation using crude oil?
-crude oil is heated until most of it has turned into a gas -the gas enters the fractionating column -the hydrocarbons at the bottom have a high boiling point and they turn back into liquids and drain out the collumn at the bottom -the shorter hydrocarbons at the top of the column have lower boiling points and they turn into a liquid and drain out at the top of the column where it is cooler.
39
where is it hot and where is it cold in a fractionating column?
cold at the top hot at the bottom short hydrocarbon top long hydrocarbons bottom
40
what is the order of the hydrocarbons in a fractionating column from top to bottom?
-LPG (liquefied petroleum gas) -petrol -naptha -kerosene -diesel -oil
41
what is petrol used for?
cars
42
what is naptha used for?
used in chemical production
43
what is kerosene used for?
airplane jet fuel
44
what is diesel used for?
diesel engines
45
what is bitumen used for?
ships and lubricating oil
46
what are the bonds between hydrocarbon molecules called?
strong covalent bonds
47
what are the bonds between different hydrocarbon molecules in crude oil called?
intermolecular forces
48
what happens when crude oil is heated?
the molecules gain kinetic energy and they might gain enough energy to overcome the intermolecular forces
49
why don't covalent bonds break between hydrocarbons?
the bonds are much stronger than intermolecular forces
50
why do intermolecular forces break more easily in small molecules?
the forces are stronger between big molecules
51
what does crude oil provide energy for?
generating electricity heating homes transport provides raw materials needed for chemicals (plastics)
52
what is cracking?
splitting up long chain hydrocarbons
53
what does cracking do?
turns long chains of alkane (hydrocarbon) molecules into smaller alkane (hydrocarbon) molecules
54
what does cracking need?
-catalyst to speed up the reaction (alluminium oxide) -large amounts of heat to break the strong covalent bonds between alkanes (hydrocarbons) (400 degrees to 700 degrees) -large amounts of pressue (70atm)
55
what does cracking produce lots of?
alkane molecules which can be used to make polymers (plastics)
56
what did volcanoes release into the atmosphere?
carbon dioxide, steam, methane, ammonia
57
what is different about an alkane and alkene?
alkenes have a double bond alkanes have a single bond
58
what are large molecules of alkanes broken down into?
alkanes and alkenes
59
what are the advantages of phytoextraction?
-requires less energy than smelting -produces less air pollution -reduces the amount of waste rock
60
what are the disadvantages of phytoextraction?
-can produce toxic chemicals -much slower process -electrolysis requires large amounts of energy
61
what are the advantages of bioleaching?
-simple process -cheap process -can use it on low grade ores -environmentally friendly and fewer waste gases produced
62
what are the disadvantages of bioleaching?
-slow process -toxic chemicals are produced -has low efficiency
63
what did the world's atmosphere start off with?
carbon dioxide water vapour hydrogen sulfur dioxide
64
how was nitrogen put in our atmosphere?
formed by ammonia reacting with oxygen released by dentrifying bacteria
65
how was oxygen put in our atmosphere?
through photosynthesis in plants
66
how much nitrogen is in our atmosphere currently?
78%
67
how much oxygen is in our atmosphere currently?
21%
68
how does human activity effect the atmosphere?
-human population increasing- more respiration- more carbon dioxide released -greater demand for electricity in lighting, cooking, heating, transport -energy consumption from burning fossil fuels releases carbon dioxide -deforestation
69
what is the effect of greenhouse gases?
-causes the average temperature of the earth to increase -can cause flooding due to polar ice caps melting -severe weather changes -extinction
70
what can we do to prevent fossil fuel emissions?
-limit our use of fossil fuels -walking or cycling instead of driving -turning your central heating down -encourage the public industry to become more energy efficient
71
what are two alternative fuels to fossil fuels?
ethanol biodesel
72
what is biofuel produced from?
vegetable oils (rapeseed and soybean oil)
73
what can you mix with biofuel?
ordinary diesel fuel which can be used to run a diesel engine
74
what are the advantages of biofuel?
-carbon neutral -engines don't need to be converted -produces less sulfur dioxide and other pollutants than regular diesel or petrol
75
what are the disadvantages of biofuel?
-we can't make enough to replace diesel -expensive to make -increases food prices
76
what is acid rain caused by?
sulfur dioxide and oxides of nitrogen when they mix with clouds they form dilute sulfuric acid and nitric acid which falls as acid rain
77
what are the main causes of acid rain?
power stations internal combustion engines
78
what are the effects of acid rain?
-causes lakes to become acidic -kills plants and animals -kills trees -damages limestone buildings and stone statues -causes metal to corrode
79
where does sulfur come from?
sulfur impurities in fossil fuels
80
how are nitrogen oxides created?
from a reaction between nitrogen and oxygen in the air
81
ignore
ignore
82
what is photochemical smog?
a type of air pollution
83
what is the dangerous aspect of carbon monoxide?
it can stop your blood carrying oxygen around your body- causes fainting, comas and death
84
how is carbon monoxide formed?
when carbon compounds are burnt without enough oxygen- incomplete combustion
85
how is particulate carbon formed?
when small pieces of solids (mainly carbon) , particulates during incomplete combustion are released into the atmopshere.
86
what is soot?
carbon particulates which have fallen back to the ground and deposited as black dust
87
what are the negative aspects of carbon particulates?
they reduce air quality, and can cause or worsen respiratory problems
88
where do we get our water from?
lakes rivers reservoirs aquifers (rocks that trap water underground)
89
what are the three main fossil fuels and where do they come from?
water vapour- combustion carbon dioxide- fossil fuels methane- decomposing rubbish and animal waste
90
explain the greenhouse effect:
-sun emits short wavelength radiation (UV light) which warms the earth -the earth loses heat my emitting long wave radiation back to space -the greenhouse gases in the earth's atmosphere absorb some of the long wavelength radiation -the greenhouse gases re-radiate this thermal radiation in all directions to earth. this warms the atmosphere
91
how can we reduce the amount of carbon dioxide in the air?
use less fossil fuels and electricity
92
how can we reduce the amount of carbon monoxide, particulate carbon and nitrogen oxides in the air?
using catalytic converters, burning less fossil fuels, driving less
93
what is potable water?
water that is filtered and safe to drink- has no impurities in it
94
what are the steps to getting potable water?
1. coagulation 2. sedimentation 3.filtration 4. chloronation
95
what is coagulation?
adding alluminium sulfate into water which causes clay, dirt and organic matter to clump together to form floc. due to gravity the floc settles at the bottom of the water tank. this makes it easier to remove the waste by filtration and sedimentation.
96
what is sedimentation?
large tanks allow floc to settle at the bottom of the tanks as sludge. then dripping water into tanks allows extra oxygen to mix with the water which provides oxygen for microbal respiration.
97
why is water dripped in a tank in sedimentation?
it allows extra oxygen to mix with the water which provides oxygen for microbal respiration
98
what is filtration?
the water moves through a layer of charcoal and coal before being filtered again using sand. Sand acts as a microfilter which traps air which increases oxygen for microbal respiration- this helps decomposition.
99
what is chloronation?
disinfecting water by adding chlorine gas- prevents disease fluroine is also added with strengths teeth and prevents tooth decay
100
why is chloronation so beneficial?
it is easy, inexpensive and reliable
101
why are some people against fluranation?
-people think it might cause cancer and tooth flekking
102
what is cryolite?
a compound added into alluminium oxide to lower it's melting/boiling point
103
what are the electrodes in alluminium oxide electrolysis made of?
graphite
104
why do the electrodes need to be replaced in alluminium oxide electrolysis?
because the oxygen molecules produced at the anode will react with the graphite electrodes which will form carbon dioxide gas
105
what do you put in and get out in alluminium oxide electrolysis?
in- alluminium oxide moxed with cryolite out- molten pure alluminium
106
why is electrolysis so expensive?
1. melting compounds like alluminium oxide requires a large amount of energy which costs money 2. a lot of energy is required for the electric current
107
what is made at the cathode in alluminium oxide electrolysis?
alluminium Al 3+ + 3e - ------- Al reduction
108
what is made at the anode in alluminium oxide electrolysis?
2o2- 4e- ------- o2 oxidation
109
what are alkanes?
hydrocarbons with single bonds only C2H2n+2
110
the elements and their carbon amounts:
1- methane 2- ethane 3-propane 4-butane
111
why are shorter hydrocarbons more useful?
-it improves the supply of fuel- helps match demand -(alkenes- shorter hydrocarbons) can be used to make polymers and other chemical products

chemistry (3 decks)

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