Option - Atmospheric Chemistry Flashcards
(98 cards)
1
Q
What is the atmosphere?
A
The atmosphere is a layer of gas that extends ~100km above the surface of the earth.
2
Q
What is the most reactive gas in air?
A
Oxygen
3
Q
Give four uses of Oxygen
A
- Steel industry (used to remove carbon and other impurities)
- Rocket Fuel
- Welding (oxyacetylene torch - oxygen is mixed with ethyne to produce a very hot flame to burn through metals)
- Combating pollution in rivers and lakes
4
Q
- Steel industry (used to remove carbon and other impurities)
- Rocket Fuel
- Welding (oxyacetylene torch - oxygen is mixed with ethyne to produce a very hot flame to burn through metals)
and - Combating pollution in rivers and lakes
are uses of?
A
Oxygen
5
Q
________ followed by _______ ________ of air is how oxygen is manufactured
A
Liquefaction followed by fractional distillation
6
Q
Give the steps of how air is manufactured
A
//air is turned into a liquid and the different gases are then boiled off at different temperatures//
- Air is filtered to remove dust and other impurities. It is then compresses to a pressure of ~6atm
- CO2 and H2O vapour are then removed (as they would solidify and block pipes) - The CO2 is removed by using NaOH and the H2O is removed using silica
- The air is then cooled to a temp of -170°C (compressed and allowed to expand suddenly)
- This cold air is then fed into a fractionating column. The temp at the top of the column if -190°C and at the bottom is -200°C. The liquid air at the bottom of the column is allowed to warm up and begin to boil. Nitrogen boils off first (-196°C) and then Oxygen (-183°C).
7
Q
Why is air filtered in the manufacturing of oxygen?
A
to remove dust and other impurities
8
Q
Why and how are CO2 and H2O removed before the air is cooled? (Manufacturing of Oxygen)
A
Because they would solidify and block pipes. the CO2 is removed by using NaOH and the H2O is removed by using silica
9
Q
How is the air cooled and to what temp is it cooled?(Manufacturing of Oxygen)
A
it is compressed and then allowed to expand suddenly and it is cooled to a temop of ~-170°C
10
Q
Where is the cold air fed into? (Manufacturing of Oxygen)
A
A fractionating column.
11
Q
What are the temperatures at the top and bottom of the fractionating column? (Manufacturing of Oxygen)
A
-190°C at the top and -200°C at the bottom
12
Q
Which gas boils off first and which gas boils off second?(Manufacturing of Oxygen)
A
nitrogen boils off first at -196°C and Oxygen boils off second at -183°C
13
Q
Give four qualities of Nitrogen
A
odourless, colourless, tasteless and very unreactive gas.
14
Q
Give four uses of Nitrogen
A
- Food Packaging (bags of crisps are usually filled with nitrogen)
- Making flammable chemicals safe (storage tanks in ships that deliver crude oil to refineries are flushes out with Nitrogen as are trucks which deliver fuel to petrol stations
- Liquid Nitrogen (temp < -196°C) used in quick-freezing of food
- used in medicine to remove warts
15
Q
Why is Nitrogen unreactive?
A
Because of the large amount of energy needed to break the triple bond in the nitrogen molecule. it is non-polar and only slightly soluble in water
16
Q
What is the most abundant gas in air and at what % is it present?
A
Nitrogen @ 78%
17
Q
Why is Nitrogen essential for plant growth?
A
as Nitrogen is needed to manufacture proteins.
18
Q
Why can Atmospheric Nitrogen be used by plants?
A
It is too unreactive and so must be changed or ‘fixed’ into nitrates in order to be used by plants.
19
Q
What is Nitrogen Fixation?
A
Nitrogen fixation is the conversion of atmospheric Nitrogen to compounds which can be used by plants. //It occurs naturally.//
20
Q
Explain how Nitrogen Fixation occurs during thunderstorms.
A
The discharge of electricity provides enough energy for the N2 and O2 to react together and form nitrogen monoxide. This then reacts with O2 to form Nitrogen Dioxide.
N2 + O2 -> 2NO
2NO + O2 -> 2NO2
21
Q
give the formula for Nitrogen Fixation during thunderstorms
A
N2 + O2 -> 2NO
2NO + O2 -> 2NO2
22
Q
What happens to the NO2 in the air after it is formed during a thunderstorm
A
This NO2 dissolves in rainwater to form nitroue acid and nitric acid which falls to eartg in rainwater and forms nitrate compounds (NO3-) in the soil
2NO2 + H2O -> HNO2 + HNO3
Plants take these nitrate compounds into their roots and use them to make protein. Animals obtain protein by eating plants or by eating other animals.
23
Q
What do plants do with nitrate compounds found in the soil
A
Plants take these nitrate compounds into their roots and use them to make protein. Animals obtain protein by eating plants or by eating other animals.
24
Q
How do animals obtain protein? (Nitrogen)
A
Animals obtain protein by eating plants or by eating other animals.
25
What are organic compunds?
Organic compounds are carbon containing compounds.
26
What does CFCs stand for?
Chlorofluorocarbons
27
Give the composition (in %) of dry unpolluted air
78% Nitrogen
21% Oxygen
1% Other gases (noble gases, carbon dioxide etc)
28
How are the gases in the atmosphere mixed?
By the rotation of the earth and by the air currents caused by the heating of the Earth by the sun
29
Comment on Nitrogen fixation on the roots of legumes.
```
Nitrogen Fixation is also carried out by nitrogen-fixing bacteria in swellings on the roots of legumes (peas, beans, clover).
//The legumes have ting nodules (swellings) on their roots that contain rhizobium bacteria. These bacteria have the ability to fix nitrogen. Thus cultivating these types of plants is a way to increase the amount of nitrogen compounds in the soil. It is unclear how these bacteria convert atmospheric nitrogen (N2) into Nitrate ions (NO3-). There is a lot of research being done to understand how this occurs.
```
30
What is the nitrogen cycle?
The sequence of events that remove nitrogen from the air and put nitrogen back into the air are summarised in the Nitrogen Cycle.
31
Discuss the presence of Ammonium salts in the excretion products of animals and the products formed when animals and plants decay.
Certain bacteria in the soil which are called nitrifying bacteria convert these ammonium salts into nitrates. Also, some bacteria attack nitrates and change them to atmospheric nitrogen. These bacteria are called denitrifying bacteria.
32
What are denitrifying bacteria?
Denitrifying bacteria attack nitrates and change them to atmospheric nitrogen.
33
How does N2 in the air enter plants?
Through natural and Artificial fixation.
- Rain and lightning
- Ammonia Fixing Bacteria
- Ammonia Plant
- From nitrogen in manure and compost which enters the soil
34
How does nitrogen from plants end up in Manure, compost etc?
- From decaying plants
- Ingested by animals which then excrete manure which contains manure
- When animals die and decay
35
How does nitrogen re-enter the air?
By denitrifying bacteria - they attack nitrates and change them back to atmospheric nitrogen
36
Give an example of a compound which contains carbon but is classed as an inorganic compound.
CO2
CO
Carbonate compounds eg. Calcium carbonate (CaCO3)
37
How is CO2 formed?
by burning C in O2
| C + O2 -> CO2
38
When CO2 dissolves in water it is acidic or basic?
| and so it turns litmus paper blue or red
acidic .... turns litmus red
39
Give the equation for the formation of Carbonic Acid
CO2 + H2O H2CO3
40
CO2 make exist in its ____ state as ______ or in its _______ state as __________ or ___________.
CO2 may exist in its free state as CO2 or in its combined state as carbonates or hydrocarbonates.
41
what is a deflagrating spoon?
A long-handled spoon with a cover, lowered into a glass vessel filled with a gas to demonstrate deflagration.
42
What happens when carbon powder is held in a deflagrating spoon over a bunsen burner and this carbon is then plunged into a jar of oxygen?
Now add water and shake. What colour will the litmus turn?
it becomes red hot , when plunged into the oxygen it glows brightly and carbon dioxide gas is formed
C + O2 ---> CO2
When water is added and the jar is shaken it is found that the carbon dioxide dissolves in the water slightly.
The solution of carbon dioxide in water changes litmus paper from blur to red; the water is acidic. this is because the water reacted with water to form a weak acid called carbonic acid. H2CO3
43
Where can you find Calcium Carbonate in nature?
Calcium carbonate is one of the most common substances found in nature. It occurs in the form of marble, chalk, or limestone.
44
Why is carbon dioxide said to be an acidic oxide?
Since it forms an acidic solution if dissolved in water.
45
In 1766, ______ _________ the discoverer of Oxygen discovered that carbon dissolved in water made for a refreshing drink.
Joseph Priestly
46
Give the equation for the production of Carbon Dioxide by reacting Hydrochlorc acid with marble chips.
CaCO3 + 2HCL ---> CaCl2 + H2O + CO2
47
What is fermentation?
fermentation is one of the methods used to produce ethanol. It is the action of yeast to help break down glucose into ethanol and CO2.
Gluscose --> ethanol + carbon dioxide
C6H1206 --> 2C2H5OH + 2CO2
48
Uses of Carbon Dioxide
- Fizz in drinks
- fire extinguishers
- solid CO2 to keeps objects cool while being transported
49
Carbon monoxide is formed when carbon is burned in a _________ oxygen supply
limited
50
If inhaled, Carbon Monoxide reacts with the __________ in the blood and reduces the ability to carry O2.
haemoglobin
51
Carbon monoxide _______ dissolve in water and _______ react with acids OR bases. For this reason it is said to be a ________ oxide.
does not
does not
neutral oxide
52
How is Carbon Dioxide removed from the atmosphere?
by photosynthesis
53
Summarise Photosynthesis
carbon dioxide + water -> glucose + oxygen
| 6CO2 + 6H2O -> C6H12O6 + 6O2
54
How is carbon dioxide added to the atmosphere
by process of respiration. This is the method by which all living things get energy from food.
55
Summarise Respiration
Glucose + Oxygen -> Carbon Dioxide + water
| C6H12O6 + 6O2 -> 6CO2 + 6H2O
56
Photosynthesis is the reverse equation of what?
respiration
57
What is the greenhouse effect?
The greenhouse effect is a natural phenomenon involving the trapping of the sun's heat energy by the atmosphere.
58
Some gases are particularly good art absorbing the heat energy given off as the Earth cools down. e.g ______, ________, _______ and ________
CO2
Methane
Water vapour
and CFC's
59
What is the greenhouse factor?
```
The greenhouse factor is a measure of the greenhouse effect caused by a particular gas relative to the same amount of CO2.
//CO2 is taken as the standard and assigned a value of one.//
```
60
What is the enhanced Greenhouse effect?
Increasing concentrations of greenhouse gases in the atmosphere may be causing the Earth to get warmer. This extra warming is called global warming.
61
What is Residence time?
the residence time is the time it takes for the greenhouse gases to be broken down in nature. CO2, CFs have a residence time of 100yrs; Methane (CH4) of 10yrs.
62
The levels of CO2 are rising as a result of ......
more fossil fuels being burned with increasing industrialisation.
63
Why does water have an over all greater effect than CO2?
```
Because of its higher concentrations.
// The amount of water vapour in the atmosphere is controlled by evaporation and condensation in the water cycle.//
```
64
Give three examples of the implications of the enhanced greenhouse effect.
1. Rise in sea level - Melting of glaciers in arctic and antarctic regions
2. Climate Changes - Climate conditions will become more extreme
3. Agriculture - rate of photosynthesis could be increased and yield of crops could be reduced by increased rainfall.
65
What is air pollution?
Air pollution is a situation that exists when a constituent in the air is present to the extent that there is significant hazard to present or future health or to the environment.
66
Gases released into the air spread throughout the atmosphere by ________.
Diffusion
67
Acid rain arises because some .....
air pollutants have acidic properties. SO2 and NO2 are the main pollutants which give rise to acid rain.
68
Three sources of Sulphur dioxide (SO2)
- volcanoes
- rotting vegetation
- burning of fossil fuels (coal)
69
Summarise and Give the equation for the formation of sulphur dioxide from the burning of fossil fuels.
The S in fuel combines with O2 to form SO2 - S + O2 -> SO2
The SO2 reacts with O2 in the air to form Sulphur trioxide 2SO2 + O2 -> 2SO3
The SO3 dissolves in rainwater to form sulphuric acid SO3 + H2O -> H2SO4
70
Summarise and give the equations for the formation of Nitrous acid from the burning of fossil fuels in factories and car engines
at high temperatures, nitrogen in air combines with oxygen to form nitrogen monoxide (Nitrogen + Oxygen -> Nitrogen Monoxide)
N2 + O2 -> 2NO
the Nitrogen Monoxide combines with oxygen in the air to form Nitrogen Dioxide
2NO + O2 -> 2NO2
The Nitrogen dioxide then dissolves in rainwater to form a mixture of nitrous acid and nitric acid
2NO2 + H2O -> HNO2 + HNO3
71
What does acid rain damage? (3x examples)
1. Damage to forests and lakes (fish deaths)
2. Washes out essential nutrients like Ca and Mg from soil so affects growth of plants
3. Damages limestone buildings and may metals also corrode
72
What is the purpose of a scrubbing station?
Power stations have installed 'scrubbing stations' to remove SO2 from the gases in the chimney stacks BEFORE they leave the power station.
73
How to 'Scrubbing Stations' work? and give the equation
As the gases pass up the chimney, jets pf wet powdered limestone are sprayed on them.
limestone + sulfur dioxide -> calcium sulfite + carbon dioxide
CaCO3 + SO2 -> CaSO3 + CO2
74
What is formed when the calcium sulfite reacts with oxygen? What can it be used for?
The calcium sulfite reacts with oxygen to form Calcium Sulfate (gypsum) which is removed as a sludge. Calcium Sulfate can be used to make plaster for the building industry.
75
Trioxygen, O3, is also known as _______
Ozone
76
Where is Ozone found?
Ozone is found in the upper part of the atmosphere (the stratosphere) where it absorbs the harmful uv radiation coming from the sun.
77
What is ozone in relation to scent? appearance? liquedation point?
pungent
pale blue gas
condenses to liquid at -112°C
78
How is ozone formed?
Ozone is formed by the reaction between an Oxygen atom and an Oxygen molecule.
The Oxygen atoms are formed when uv light breaks the oxygen molecule into Oxygen atoms
O2 -> O* + O*
(Photodissociation - the breaking of a bond using radiation )
The oxygen free radicals are very reactive and react with Oxygen to form ozone.
O* + O2 -> O3
When the ozone formed absorbs uv radiation, photodissociation of ozone occurs
O3 -> O2 + O*
Most of these O atoms react with O2 molecules to reform Ozone.
Some of the O atoms produced destroy Ozone molecules by converting them to Oxygen molecules
O* + O3 -> 2O2
The O2 molecules are broken down by uv light to form O atoms which lead to the production of ozone.
79
Where is ozone being made and destroyed?
in the stratosphere
80
Where specifically is the level of ozone being depleted?
Above the Arctic
81
What is the main cause of ozone depletion?
CFC's
82
What are CFC's?
CFC's are compounds that contain chlorine, fluorine and carbon.
They are used in fridges, freezers, air conditioners and aerosols.
83
Are aerosols reactive? How long is their residence?
They are unreactive and have a residence time of 100 years.
84
Where are they broken down?
| Give Equation.
They are broken down when they reach the stratosphere, by the high level of uv radiation.
CCl3F -> CCl2F + Cl*
The Cl atoms attack ozone to form O and Cl atoms
O3 + Cl* -> O2 + ClO*
The chlorine oxide is very reactive and attacks an oxygen atom
ClO* + O* -> Cl* + O2
More Cl atoms are released to attack the ozone - chain reaction occurs.
85
What prevents the build up of chlorine atoms?
| Give an example.
Other molecules react with chlorine and prevent their concentration building up.
Methane (CH4) reacts with chlorine to form hydrogen chloride which is removed in raindrops.
86
What are used as a non-damaging alternative to CFC's? Why are they not a perfect replacement?
Hydrochlorofluorocarbons are used as non-damaging alternatives to CFC's. However they are greenhouse gases and contribute to global warming.
87
Why is the greenhouse effect essential for life on Earth?
it makes temperatures (climate) suitable for life
88
Give two human activities that have enhanced the natural greenhouse effect, particularly in recent times.
burning fossil fuels // gas flaring (extraction, processing) // transporting fossil fuels) //
population rise // urbanisation // rice production (paddy fields) // farming livestock (cattle, sheep, goats, deer, pigs, chickens, etc) // deforestation //cement production // garbage (waste) disposal // NOx (N2O, NO2) from fertilizer industry (cars) // CFCs (HCFCs, halocarbons) // etc
89
Give two reasons why different atmospheric gases have different impacts on the greenhouse effect.
present in different quantities / abundances different //
different abilities to absorb heat (infra-red) energy / different greenhouse factors // different residence times (broken down at different rates) in atmosphere
90
Compare the contributions of carbon dioxide and water vapour to the natural greenhouse effect.
Account for the difference
water vapour has a greater (greatest, larger, largest) greenhouse effect (impact)
water vapour is the most (more) abundant (plentiful, present in greater
concentration) / carbon dioxide significantly less abundant
91
What is the beneficial effect of the ozone layer?
absorbs {shields earth (us) from} ultraviolet (uv) radiation
92
How is ozone formed in the stratosphere?
high energy {frequency (short wavelength)} radiation / ultraviolet (uv)
radiation / UVC //
breaks oxygen molecules (O2) into separate atoms (radicals) /
O2 → 2O / O2 → 2O• //
these oxygen atoms (O, O•
, radicals) react with oxygen molecules (O2) to form
ozone (O3) / O + O2 → O3 / O•
+ O2 → O3
93
CFCs release chlorine radicals when they photodissociate in the stratosphere.
Describe using balanced equations why chlorine radicals are so damaging to the ozone layer.
Cl + O3 → ClO + O2 / Cl• + O3 → ClO• + O2 //
ClO + O → Cl + O2 / ClO• + O•→ Cl•+ O2 //
chain reaction / process repeats (continues) / Cl (Cl•) attacks another O3 (ozone molecule) /
repeat line 1 (3 × 3)
[Radical dots not essential here.]
94
Why are HCFCs significantly less damaging to the ozone layer than CFCs?
broken down more easily than
| CFCs
95
greenhouse gases - Explain this term
gases that absorb heat (energy, infra-red radiation) in atmosphere
96
State one global climate change implication of failure to control greenhouse gas emissions.
global warming / melting polar ice-caps / rise in sea levels / flooding / wildlife endangered / wildlife habitats endangered, etc
97
Arrange water vapour, methane, carbon dioxide and a typical chlorofluorocarbon,
in order of their increasing greenhouse factors.
Which of these gases contributes most to the greenhouse effect?
Describe one way that chlorofluorocarbons are broken down in the stratosphere.
ARRANGE: water vapour, carbon dioxide, methane, typical CFC (6)
WHICH: water vapour (3)
DESCRIBE: broken down by ultraviolet (uv) radiation (rays, light) /release (give) chlorine atoms (chlorine free radicals, Cl, Cl•)
98
Suggest two ways by which Ireland could reduce its emissions of greenhouse gases.
ban use of CFCs //
use CFC substitutes //
use HCFCs //
recycle (dispose properly of) refrigerators (air conditioners) with CFCs //
reduce number of ruminants (cattle, sheep, goats, deer, etc) //
collect methane gas escaping from dumps (slurry) //
use biogas digesters //
plant more trees (avoid deforestation) //
use renewable (wind, waves, tides, solar) power (energy) //
reduce fossil fuel dependency (use) //
use public transport (bus, train, etc) //
walk (cycle) instead of driving (using transport relying on fossil fuel) // use nuclear power (energy) //
