GCSE Workbook Chemistry of the atmosphere
GCSE Chemistry 8462. GCSE exams June 2018 onwards. Version 1.0 21 April 2016
4.9 Chemistry of the atmosphere The Earth’s atmosphere is dynamic and forever changing. The causes of these changes are sometimes man-made and sometimes part of many natural cycles. Scientists use very complex software to predict weather and climate change as there are many variables that can influence this. The problems caused by increased levels of air pollutants require scientists and engineers to develop solutions that help to reduce the impact of human activity.
4.9.1 The composition and evolution of the Earth's atmosphere 4.9.1.1 The proportions of different gases in the atmosphere Content
Key opportunities for skills development
For 200 million years, the proportions of different gases in the atmosphere have been much the same as they are today:
MS 1c
• about four-fifths (approximately 80%) nitrogen • about one-fifth (approximately 20%) oxygen • small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
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To use ratios, fractions and percentages.
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4.9.1.2 The Earth's early atmosphere Content
Key opportunities for skills development
Theories about what was in the Earth’s early atmosphere and how the atmosphere was formed have changed and developed over time. Evidence for the early atmosphere is limited because of the time scale of 4.6 billion years.
WS 1.1, 1.2, 1.3, 3.5, 3.6, 4.1
One theory suggests that during the first billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans. At the start of this period the Earth’s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas. Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia. When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere. No knowledge of other theories is required. Students should be able to, given appropriate information, interpret evidence and evaluate different theories about the Earth’s early atmosphere.
4.9.1.3 How oxygen increased Content
Key opportunities for skills development
Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis, which can be represented by the equation:
WS 1.2 An opportunity to show that aquatic plants produce oxygen in daylight.
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
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GCSE Chemistry 8462. GCSE exams June 2018 onwards. Version 1.0 21 April 2016
4.9.1.4 How carbon dioxide decreased Content
Key opportunities for skills development
Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis. Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon. WS 1.2, 4.1
Students should be able to: • describe the main changes in the atmosphere over time and some of the likely causes of these changes • describe and explain the formation of deposits of limestone, coal, crude oil and natural gas.
4.9.2 Carbon dioxide and methane as greenhouse gases 4.9.2.1 Greenhouse gases Content
Key opportunities for skills development
WS 1.2 Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. Water vapour, carbon dioxide and methane are greenhouse gases. Students should be able to describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.
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4.9.2.2 Human activities which contribute to an increase in greenhouse gases in the atmosphere Content
Key opportunities for skills development
Some human activities increase the amounts of greenhouse gases in the atmosphere. These include: • carbon dioxide • methane. Students should be able to recall two human activities that increase the amounts of each of the greenhouse gases carbon dioxide and methane. Based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change. However, it is difficult to model such complex systems as global climate change. This leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased. Students should be able to:
WS 1.2, 1.3, 1.6
• evaluate the quality of evidence in a report about global climate change given appropriate information • describe uncertainties in the evidence base • recognise the importance of peer review of results and of communicating results to a wide range of audiences.
4.9.2.3 Global climate change Content
Key opportunities for skills development
An increase in average global temperature is a major cause of climate change.
WS 1.5
There are several potential effects of global climate change. Students should be able to: • describe briefly four potential effects of global climate change • discuss the scale, risk and environmental implications of global climate change.
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GCSE Chemistry 8462. GCSE exams June 2018 onwards. Version 1.0 21 April 2016
4.9.2.4 The carbon footprint and its reduction Content
Key opportunities for skills development
The carbon footprint is the total amount of carbon dioxide and other WS 1.3 greenhouse gases emitted over the full life cycle of a product, service or event. The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane. Students should be able to: • describe actions to reduce emissions of carbon dioxide and methane • give reasons why actions may be limited.
4.9.3 Common atmospheric pollutants and their sources 4.9.3.1 Atmospheric pollutants from fuels Content
Key opportunities for skills development
The combustion of fuels is a major source of atmospheric pollutants. Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur. The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere. Students should be able to: • describe how carbon monoxide, soot (carbon particles), sulfur dioxide and oxides of nitrogen are produced by burning fuels • predict the products of combustion of a fuel given appropriate information about the composition of the fuel and the conditions in which it is used.
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WS 1.2
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4.9.3.2 Properties and effects of atmospheric pollutants Content
Key opportunities for skills development
Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected. Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain. Particulates cause global dimming and health problems for humans. Students should be able to describe and explain the problems caused by increased amounts of these pollutants in the air.
WS 1.4
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Helping yourself Read the section on Atomic structure and the Periodic table in your textbook Read the relevant sections of these websites bbc.co.uk/schools/gcsebitesize/chemistry gcsescience.com docbrown.info revisioncentre.co.uk youtube for video tutorials other teachers!
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The Atmosphere The atmosphere is a mixture of ...................... that surround the earth. It gets thinner the further away from the surface. Air is a mixture of gases in the lower part of the atmosphere. 99% is made up of ........................... and ................................. and has been fairly constant for the last 200 million years. There are small amounts of other gases which make up the final 1%. Mainly ............................ but small amounts of water and carbon dioxide. The amount of water vapour changes depending on the .................................. so is often discounted. Air also contains trace amounts of harmful gases such as sulphur dioxide, nitrogen oxide and carbon monoxide. These are formed by volcanoes and form plants and animal decay. Some are made by human activity.
Gas
Formula
Nitrogen
N2
Percentage in dry air 78
Oxygen
O2
21
Argon
Ar
0.9
Carbon dioxide Other gases
CO2
0.04 traces
Air can be separated by fractional distillation. Air is cooled too about -200°C and then warmed up again until the fractions boil at different temperatures.
Nitrogen is unreactive and used in food packaging Oxygen is used to help patients breathe in hospitals. Argon is used in bulb filaments The volume of Oxygen in the air can be found by passing a fixed volume of gas over hot Copper and noting the change in volume. This equates to the amount of Oxygen reacted with copper to form solid copper oxide.
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Early Atmosphere The earth is about 4.5 ............................. years old and we are unsure about the early atmosphere, where it came from and what it was composed of. Gases might have come from inside the earth, released by .......................... activity or they might have come from ........................ colliding with the earth. The gases were thought to be .........................................., water vapour, ................................. and ...................................... because those are what volcanoes release today. Neighbouring planets such as Venus and Mars have atmospheres that are 95% Carbon dioxide. Earth might have been the same and the evolution of life transformed that. It is thought that there was little or no oxygen in the early atmosphere because oxygen is not released in volcanoes. Water vapour in the atmosphere is thought to have ............................... and formed the oceans. The proportion of carbon dioxide went down because it was locked away in .................................... rock and in fossil fuels, it was absorbed by plants in ........................................ and it ......................................... in the oceans.
We do not know how life on earth started but it has been shown that given the right conditions, ............................................ form from methane, ammonia and hydrogen Amino acids are essential to life. This is an experiment that was conducted by Urey and Miller. They assumed that the early atmosphere was full of ..............................................
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Evolution of the Earth’s atmosphere A. Oxygen and Carbon dioxide checks and balances Removal of carbon dioxide (CO2): ......................................* in green land plants absorbs carbon dioxide to form ............................... (and oxygen), then some plant biomass is converted to animal biomass. Some of the CO2 will .................................... in the seas/oceans => This may be further changed in photosynthesising marine organisms to produce biomass, forming soluble ............................... and insoluble minerals eg calcium carbonate (sedimentary limestone rock) as the shelly remains of creatures and coral etc., decay (without oxygen) of any organic material from dead plant and animal remains to form the ................................... coal, oil and gas over millions of years. * Photosynthesis: water + carbon dioxide + sunlight energy ==> glucose sugar + oxygen
!!! ! ! + !"!! ! → !! !!" !! (!") + !!! (!)
Production of carbon dioxide: Natural burning of biomass like forests, plant and animal ...........................**, biological decay of plant and animal material, 'mans' burning/............................. of fossil fuel, volcanic activity eg the thermal decomposition of minerals like carbonates in magma/lava. ** Respiration: glucose sugar + oxygen ==> water + carbon dioxide + energy (exothermic, energy given out) !! !!" !! !" + !!! ! → !!! !(!) + !"!! (!)
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Oxygen balance: The main process of CO2 removal by ................................. also produces ....................... ............................ and combustion (natural/man) mainly remove the oxygen from our atmosphere. So this means the Carbon-Cycle effectively maintains a constant percentage of oxygen in the atmosphere as well as controlling the carbon dioxide levels. (Note: as far as we know the Greenhouse Effect will not significantly change the oxygen level in the Earth's atmosphere). Global warming, temperature and CO2 imbalance: The average temperature of the Earth depends on the net effect of the Sun's input and the Earth's output of energy [mainly by heat/infrared (ir) radiation]. However, the relatively rapid rate of burning massive amounts of fossil fuels over the last few hundred years is threatening this and the CO2 balance. The CO2 in the atmosphere absorbs some of the re-radiated.............................. to keep the Earth warm and a constant CO2 concentration, also means a steady .............................. The increasing CO2 levels means more ir is absorbed and the global temperatures are rising - the ............................ Effect. This global warming is predicted (maybe happening?) to: affect ........ levels by melting glaciers, change in weather ....................... eg more drought in Africa, more rain and storms in other parts of the world, forcing change in agriculture management with weather/temperature changes etc. etc. but its all a bit uncertain! B. The early atmosphere The early Earth atmosphere consisted of mainly carbon dioxide, water vapour and small amounts of ammonia and methane from intense ............................... activity (mainly in the first billion years!). There would be little or no oxygen (rather like on Mars or Venus today).
Seas and oceans would form from condensed water vapour as the early Earth surface ............................. down. Carbon dioxide and ammonia would dissolve in this water.
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The carbon dioxide could form soluble sodium .................., sodium hydrogencarbonate or calcium hydrogencarbonate and insoluble calcium carbonate. These turn into rocks. Primitive bacterial life evolved about 3500 million years ago (3.5 billion y) and the first green algae like plants from about 2000 million years ago (2.0 billion y). The increasingly successful evolution of green ................................ plants colonising both land and water, produced an increasingly ....................... richer atmosphere and in so doing .................. most of the carbon dioxide from the original early atmosphere. This 'oxygenated' atmosphere would be 'polluting' and 'toxic' to many microorganisms which could not tolerate oxygen, having evolved in a non-oxygen environment. However, by 1000 million (1 billion y) years ago, there was sufficient oxygen to allow the evolution of respiring animal life.
Ammonia would be converted to soluble .......................... mainly by nitrifying bacteria or, to a small extent, ammonia would be directly ......................... to nitrogen gas by the newly formed oxygen. The nitrates are absorbed by plants to form proteins or converted to atmospheric nitrogen by denitrifying .......................... Methane would be ........................... to carbon dioxide and water by the new 'oxygenated' atmosphere. Ozone (O3) would now be formed and this would absorb and filter out much of the ............................. light that is harmful to many organisms. This uv filtering would then allow the much wider evolutionary development of plant and animal organisms
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The Greenhouse effect
Green House effect
Venus is too hot, Mars is too cold, but Earth has an average surface temperature between the boiling and freezing point of water and is thus suitable for .............
This is not simply because of the distance the planets are away from the earth and therefore getting just the right amount of solar radiation. Earth’s moderate temperature is a result of having the right kind of .................................... Parts of our atmosphere act like an insulating blanket of just the right thickness trapping sufficient solar radiation in as to keep the average global temperature in a pleasant range. The blanket is a collection of atmospheric gases which we call ‘.................................. gases’ based on the idea that they ‘trap’ heat like glass does in a greenhouse. These gases are mainly ...................... vapour (H2O), .................................... (CO2), ....................................... (CH4) and ............................................. (N2O).
Solar Radiation The sun radiates vast quantities of energy into space across a wide spectrum of wavelengths. Most of the sunlight is concentrated in the visible and near-visible parts of the
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spectrum. The narrow band between ............................nm we call visible light accounts for 43% of the total radiation that is emitted. 7-8% is in the higher energy Ultra-violet part of the spectrum and the remaining 49% or so is less energetic than visible light and has longer wavelengths. This lies in the 700-1000nm range and us called thermal infrared. Various components in the atmosphere absorb ultraviolet and infrared solar radiation before it reaches the earth’s surface but the atmosphere is pretty transparent to visible light. This visible light is .......................... by land, oceans and vegetation at the surface and is transformed into ....................... and re-radiated in the form of invisible infrared radiation. It would simply re-radiate back out into space but the reradiated energy is absorbed by ................................ gases in the atmosphere which then further re-radiated the heat in all directions thereby reducing the amount that would radiate out into space and holding it in the .................................. This is much like the glass of a greenhouse works: being transparent to incoming visible solar radiation but opaque to outgoing infrared radiation thus trapping some in. This is why the earth enjoys temperatures suitable for our active and complex biosphere. This is about 33 C warmer than if there were no greenhouse gases. The average or expected conditions is what we call the climate. Greenhouse gases. ......................................... is a greenhouse gas consisting on a carbon atom bonded to two oxygen atoms covalently. These bonds can absorb infrared radiation which causes the molecule to .............................. more vigorously. Eventually the vibrating molecule will re-emit the radiation and it will probably be absorbed by another carbon dioxide molecule close by. This absorption-emission-absorption cycle has the effect of keeping heat ............................. to the surface of the earth and keeping it from the cold of space. All greenhouse gases are able to change their vibrations when the absorb infrared radiation.
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Albedo effect The type of surface which sunlight also encounters is an important factor. Forests, grasslands, oceans, icecaps, deserts and cities all absorb, reflect ad radiation differently. Ice caps reflect a lot of sunlight back out to space as visible light which ..................... absorbed by greenhouse gases. Deserts strongly absorb visible radiation and remit it out again as infrared which ........................ be absorbed by greenhouse gases in the lower atmosphere. Extensive cloud cover also means a lot of visible sunlight doesn’t reach the surface and is reflected out to space as visible light. The Enhanced Greenhouse effect This has been known about since the 1800s but what is becoming clear is that ............................. of greenhouse gases in the atmosphere are changing. We know this from over 50 years of data and carbon-13 dating of ice cores and tree rings. This means that the Earth’s incoming and outgoing radiation is out of balance forcing the climate to change. The carbon cycle Of the greenhouse gases ..............................is of greatest concern as it contributes most to the enhanced greenhouse effect. Carbon dioxide is part of a complex process called the ..................... cycle where carbon atoms within molecules are transferred between reservoirs. Processes which release 8/30
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carbon dioxide into the ........................... are called ........................ and those which removed it are called ................................... Carbon is continually exchanged and recycled among the reservoirs through natural processes. These occur at various rates ranging from daily fluctuations (respiration rates over the day) to seasonal (such as the growing season of plants) to long term (changes in carbon dioxide levels in the oceans) to very long term cycles over hundreds of millions of years (such as weathering of carbonate and silicate rocks). Fossil fuels form a relatively small part of these natural geologic cycles. On a human timescale the atmosphere exchanges carbon with three main reservoirs: the terrestrial ............................., the ........................... and ..................... fuels. The Terrestrial biosphere is the part of the earth that supports organisms living on land and includes plants, animals, soil microbes and decomposing organic material. Carbon is the main constituent of organic molecules and so this is a very large reservoir of carbon. Exchange of carbon dioxide with the atmosphere arises from ........................... and burning and ..................................... The main impact humans have upon the natural balance here is ............................. and poor land management.
Oceans are continually exchanging carbon dioxide with the atmosphere. Carbon dioxide is ............................ and most of the earth’s surface is water. There is about 50 times more carbon dioxide in the oceans than in the biosphere or atmosphere. In addition to this organisms within the marine biosphere photosynthesis and respire carbon dioxide. Increases in levels of carbon dioxide increases the ................................ of the oceans. Over the course of millions of years as biomass from dead plant matter and microorganisms accumulated in the sediment and subjected to high pressure and temperature it was turned into ............................... fuels (coal, oil and natural gas). Since the industrial revolution in the 1800s humans have been burning these and releasing carbon into the atmosphere far quicker than the reverse process. Atmospheric carbon dioxide levels have increased by 38% since preindustrial times and are higher than any in time in the past 800,000 years.
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Enhanced Greenhouse effect Carbon dioxide will remain in the atmosphere on the human timescale which will have significant implications for the radiation imbalance and result in an enhances Greenhouse effect which will alter the global ................... for centuries to millennia. It will eventually be absorbed into the ................................
Climate
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The climate is the general climatic conditions over a ..................... period of time. It is the sum of all statistical information that helps describe an area or region. Weather is the ................................ atmospheric conditions (temperature, rainfall, wind, humidity etc). The climate is the expected conditions, the weather is the actual condition. Although an area’s climate is always changing, the changes do no usually occur on a time scale that immediately obvious to us. Weather changes date to day. Weather and climate are different but related. A change in one produces a change in another. A climate is determined by both natural and anthropogenic factors. The natural elements include the atmosphere, geosphere, hydrosphere and biosphere while human factors can include land and resource uses. Changes in the factors can cause local regional or global changes in the climate. We have measured the temperature of the climate directly over the last 130 years and we have measured the temperature of the climate indirectly looking fossil records. From this we can see that the earth’s climate has changed. Some fossil records show that these are somewhat cyclical with period of global warming followed by ice ages.
Global climate is changing. Based on peer-reviewed ............................, most scientists believe that this is in part due to the enhanced green house effect and the build up of higher levels of carbon dioxide in the atmosphere resulting from the burning of fossil fuels but what that means to humans and the ecosystem is largely unknown.
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Problems of the Greenhouse Effect The greenhouse effect causes trouble by raising the ....................... of the planet. The actual rise is not very much, but the Earth's ecosystem is very fragile, and small changes can have large effects: •
Global warming could ......... the world's ice caps and glaciers, causing an increase in sea levels and making many coastal areas ............................
•
It could also affect weather patterns, causing .............., flooding and hurricanes.
•
To meet the increasing demand for energy without damaging the environment further; countries need to find new types of ................... energy, industries need to use energy .................. and people need to ..................... energy.
Carbon footprint and its reduction The carbon footprint is the ..................... amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event. It can be reduced by reducing the emissions of carbon dioxide and methane gases. Reduce Your Carbon Footprint From Driving
• Alternatives to driving. When possible, walk or ride your bike in order to avoid carbon emissions completely. Carpooling and public transportation drastically reduce CO2 emissions by spreading them out over many riders. • Drive a low carbon vehicle. • Don’t buy a minivan or SUV if you don’t need 4WD and/or will only occasionally need the extra space. Avoid roof-top boxes, which cost much more, increase aerodynamic drag, and decrease fuel economy. • Driving style. Speeding and unnecessary acceleration reduce mileage by up to 33%, waste gas and money, and increase your carbon footprint. • Tyre inflation and other tuning. Properly inflated tires improve your gas mileage by up to 3%. It also helps to use the correct grade of motor oil, and to keep your engine tuned, because some maintenance fixes, like fixing faulty oxygen sensors, can increase fuel efficiency by 8/26 8/30
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up to 40%. • Avoid traffic. Being stuck in traffic wastes gas and unnecessarily creates CO2. Use traffic websites and apps and go a different way or wait. • Misc. Combine errands to make fewer trips. Remove excess weight from your car. Use cruise control. Reduce Your Carbon Footprint From Air Travel • General. Until petroleum-based aviation fuel is replaced, you should avoid flying when possible, fly less frequently, fly shorter distances, and fly economy class. • Leisure Air Travel. Take fewer and longer vacations that are far away, and more frequent and driveable “staycations” closer to home. • Work Air Travel. Increase your use of video-conferencing tools like Skype and Facetime. • What class? Economy class is best, for the same reasons as carpooling and public transportation. Each flyer’s share of a flight’s carbon emissions is relatively less because it’s spread out over more people. • Don’t fly on private jets. Fly first or business class if you must, because at least those seats • Don’t be a space tourist.
Reduce Your Home Energy Carbon Footprint • Insulate and seal your home. Reduce drafts and air leaks with caulk, insulation, and weather stripping. • Appliances. Make energy efficiency a primary consideration when choosing a new furnace, air conditioning unit, dishwasher, or refrigerator. • Lighting. Turn off lights you’re not using and when you leave the room. Replace incandescent light bulbs with compact fluorescent or LED ones. • Thermostat. Don’t set it too high or low. Install a programmable model to turn off the heat/air conditioning when you’re not home. • Solar. Add solar panels to the roof of your home. This costs a little more than the above options, but many providers offer financing options which minimize upfront costs. Reduce Your Carbon Footprint From Food • Eat locally-produced and organic food. It has been estimated that 13% of U.S. greenhouse gas emissions result from the production and transport of food. • Cut the beef and dairy. It takes a lot of resources to raise cows, and it’s especially bad if you buy beef from somewhere like Brazil, where it was grazed on land that used to be tropical forest but was cleared for agricultural use. Deforestation is a top contributor to carbon emissions and thus climate change.
Other Ways to Reduce Your Carbon Footprint • Water usage. Lower the amount of energy used to pump, treat, and heat water by washing your car less often, using climate-appropriate plants in your garden, installing drip irrigation so that plants receive only what they need, and making water-efficient choices when
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purchasing shower heads, toilets, dishwashers and washing machines. • Reuse and recycle. It has been estimated that 29% of U.S. greenhouse gas emissions result from the “provision of goods,” which means the extraction of resources, manufacturing, transport, and final disposal of “goods” which include consumer products and packaging, building components, and passenger vehicles, but excluding food. • Support clean energy sources. Whenever you can, advocate for clean alternatives to fossil fuels, such as wind, solar, geothermal, and appropriately designed hydroelectric and biomass energy projects. • Offsetting Your Carbon Footprint Carbon offsetting should not be done in place of taking steps to reduce one’s carbon footprint. Carbon offsetting and carbon footprint reduction should be done in tandem.
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Atmospheric pollutants from fuel
Flooding
Drought
Fossil fuels contain the element .................. or compounds of sulphur. When the fuel is burned the sulphur also burns to form ........... ............. This is an ........ gas and dissolves in rainwater, it then reacts with water and oxygen to form a very dilute solution of ............. acid. Sulphur dioxide: A harmful gas and lung irritant and contributed to 5000 extra deaths in the great 'London Smog' in the 1950's. The e.g. formation of acid rain has several bad effects on the environment • • •
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the low pH causes plant damage, particularly ..................., ................... certain life forms and so damages eco cycles and food chains in rivers or lakes harming wildlife like trout, increases the '.......................' corrosion rates of building stone (particularly limestone).
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Death of flora
Damage to buildings
High temperature combustion also produces other pollutants including ... Nitrogen oxides: NO is formed in ........... engines and changes to NO2, which is acidic, contributing further to acid rain (above), and are also involved in the chemistry of '................... smog' - which produces chemicals harmful to respiration and eyes. Many of the reactions are initiated by sunlight. Nitrogen monoxide is formed in high temperature combustion situations nitrogen + oxygen ==> nitrogen monoxide N2(g) + O2(g) ==> 2NO(g) and in air the nitrogen monoxide rapidly combines with the .............. in air nitrogen monoxide + oxygen ==> nitrogen dioxide 2NO(g) + O2(g) ==> 2NO2(g) Carbon monoxide CO: ................ and also involved in the chemistry of 'photochemical smog'. This is formed by ............... combustion Particulates and Unburned hydrocarbons, CxHy, which can be .............................. and are also involved in photochemical smog chemistry. Particulates are also responsible for global .......................
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Global Dimming from smoke
Photochemical smog
But ................. converters can significantly reduced these three unwanted emissions using platinum-rhodium transition metal catalysts, these are dispersed on ceramic bed to give a big ................... area for the best reaction rate.
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D15.1
More about the atmosphere
Name
Class
Date
Draw arrows and labels on the diagram below to show what happened to the gases in the Earth’s early atmosphere and how the current atmosphere developed. Include as much detail as you can. Do it in pencil first in case you change your mind. One arrow and label have been done to show you what to do.
The early atmosphere water vapour
carbon dioxide
methane
ammonia
water vapour cooled and condensed
oceans
plants
sedimentary rock
denitrifying bacteria
fossil fuels
D nitrogen
oxygen
The current atmosphere
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Mr269 Singh
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802WS
GCSE Atm 04 Š RWGrime
19/08/16
The atmosphere - then and now 1)
Where did the gases come from that formed the atmosphere of the Earth when it was young? (1)
2)
What gases did the early atmosphere consist of?
(4)
3)
What was the main gas?
(1)
4)
Which planets have an atmosphere similar to that of Earth when it was young? (2)
5)
Where did the water come from that formed the oceans?
(1)
6)
What led to the formation of oxygen?
(2)
7)
What has happened to the methane, ammonia and carbon dioxide that was in the atmosphere (write word equations where appropriate)? (6)
8)
Nitrogen is the major component of the atmosphere today. Explain how it was produced. (4)
9)
What is the formula of ozone and what was it formed from?
(2)
10) What did the formation of the ozone layer allow to happen.
(1)
11) What is the composition of dry air today?
(4)
12) Give three ways in which carbon dioxide is released into the atmosphere.
(3)
13) Give three ways in which carbon dioxide is removed from the atmosphere.
(3)
14) Explain why carbon dioxide is produced when most fuels are burnt.
(1)
15) Explain why the proportion of carbon dioxide remained roughly constant for the last 200 million years, but has started to rise recently. (2) 16) What problems may this increasing amount of carbon dioxide cause? (2) 17) Explain why the proportion of oxygen has remained roughly constant for the last 200 million years. (2)
GCSE Atm 04 Š RWGrime
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Evidence for the Early Atmosphere - Exercise
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Climate change and global warming 1. How often does Earths climate naturally change? __________________ 2. As well as warm periods what do we also get? ______________________________________________________ 3. What happened in the last century? ___________________________ ______________________________________________________ 4. By how many degrees has Earths climate changed? ________________ 5. What do scientists believe caused the temperature change? ______________________________________________________ ______________________________________________________ 6. What causes the most pollution? ______________________________ ______________________________________________________ ______________________________________________________ 7. What do fossil fuels release? ________________________________ 8. What do greenhouse gases do? _______________________________ ______________________________________________________ ______________________________________________________ 9. Describe the greenhouse effect ______________________________________________________ ______________________________________________________ ______________________________________________________ 10. What makes extra greenhouse gases? __________________________
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______________________________________________________ 11. What year was the warmest in measured history? _________________ 12. What are some effects of global warming? ______________________ ______________________________________________________ ______________________________________________________ ______________________________________________________ 13. What are the two models for climate change? ____________________ ______________________________________________________ 14. What would the effect of global warming be on weather/hot areas/flooding? __________________________________________ ______________________________________________________ ______________________________________________________ 15. What would cutting gas emissions do? __________________________ ______________________________________________________ ______________________________________________________ 16. How can we help slow down climate change? ______________________ ______________________________________________________ ______________________________________________________ ______________________________________________________
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Acid Rain Problems 1. Why would unpolluted rainwater be classified as acidic? _______________________________________________________ _______________________________________________________ 2. What is the pH of unpolluted rainwater – does this match your answer to question 1? ______________________________________________________ 3. What are the gases that cause acid rain? _______________________________________________________ 4. Where does sulphur dioxide come from?
5. Where does nitrogen dioxide come from? _______________________________________________________ _______________________________________________________ 6. Why is acid rain a problem? _______________________________________________________ _______________________________________________________ 7. How does acid rain affect trees? _______________________________________________________ 8. How does acid rain affect fish? _______________________________________________________ 9. How does pollution from the UK affect other countries? _______________________________________________________ _______________________________________________________ 10. How would you stop acid rain? _______________________________________________________ _______________________________________________________ _______________________________________________________ 11. Do you think other people would find it easy to follow your suggestions?
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Think creatively
1. Draw a timeline of the evolution of the earth 2. Draw a flow diagram of the processes involved in the atmosphere’s change. 3. Report as a journalist on what a company is doing to reduce it’s carbon footprint. 4. Write a government public information leaflet to help households reduce their waste. 5. In the reporting of Global warming, many unsubstantiated claims are made by journalists that have later been found to be false. What damage does this do to science? 6. Write a tourist brochure to the world in 200 years time after a 5 degree temperature increase.
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Taking it further This is a topic about environmental chemistry that affects us all. A lot of the chemistry associated with the atmosphere is a lot more complicated. To what extent are we sure of the science of global warming? To what extent are we sure about the effects that it is having? Do an internet search for a case study for acid rain. What was done to reduce it as a problem? Do you live in a city where smog is a problem? What contributes towards smog and what steps can be taken by individuals, business, local and national government and globally to reduce this? Take an audit of your carbon footprint. If you were to justify this to a jury in court, could you and how would you go about arguing to defend it? Books to read: The amount of books on the subject are endless. Here are a few: Merchants of doubt: How a Handful of scientists obscured the truth on issues from Tabacco smoke to Global Warming, Naomi Oreskes Six Degrees, Mark Lynas The Sixth Extinction: An Unnatural History, Elizabeth Kolbert An Inconvenient Truth: The Planetary Emergency of Global Warming and What We can Do About It, Al Gore Unstoppable: Harnessing science to change the world, Bill Nye
Documentaries on climate change: An Inconvenient Truth, 2006, Al Gore Meat The Truth, 2008 The Island President, 2011 The 11th Hour, 2007 The Age of Stupid, 2009 Chasing ice, 2012 If this is something you feel strongly about, why not do something about it? Join the pupil group campaigning for the school to reduce its carbon footprint.
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Exam Questions 6.
Billions of years ago, the Earth’s early atmosphere was probably like the atmosphere of Venus today. The table shows a comparison of the atmospheres of the Earth and Venus today. Percentage composition of atmosphere
Name of gas
Earth today
Nitrogen
78
Oxygen
21
Argon
0.97
Carbon dioxide
0.03
Average surface temperature
20 ºC
(a)
Use the names of gases from the table to complete the sentences. (i)
In the Earth’s atmosphere today, the main gas is .................................................. . (1)
(ii)
In the Earth’s atmosphere billions of years ago, the main gas was ............................................................ . (1)
(b)
(i)
Scientists do not know the accurate composition of the Earth’s early atmosphere. Suggest why. ........................................................................................................................... ........................................................................................................................... (1)
(ii)
Use information from the table to answer this question. Water vapour is present in the atmospheres of the Earth and Venus today. The Earth’s surface is mainly covered by water. Suggest why there is no water on the surface of Venus. ........................................................................................................................... ........................................................................................................................... (1)
(c)
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The diagram shows how carbon dioxide is removed from the Earth’s atmosphere.
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Describe what happened to the carbon dioxide in the Earth’s early atmosphere. Use the diagram to help you. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (3)
(Total 7 marks)
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3.
(a)
Apart from water vapour, two gases account for about 99% of the present atmosphere of our planet. What are the names of these gases? .......................................................... and ........................................................ (1)
(b)
Scientists now have evidence that, over three billion years ago, our planet’s atmosphere was mostly a mixture of water vapour, carbon dioxide, methane and ammonia. Since then the mixture has gradually changed. (i)
Suggest why there is now less water vapour in the atmosphere. .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... (2)
(ii)
Suggest why there is now less carbon dioxide in the atmosphere. .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... .......................................................................................................................... (2)
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10 4 (d)
Do not write outside the box
Complete the displayed structure of the product in the equation.
n
H
H
C
C
H
C 6H 5
C
styrene
C
poly(styrene) (2 marks)
____ 10 5
The amount of carbon dioxide in the Earth’s atmosphere has changed since the Earth was formed. The amount of carbon dioxide continues to change because of human activities.
5 (a)
Cement is produced when a mixture of calcium carbonate and clay is heated in a rotary kiln. The fuel mixture is a hydrocarbon and air. Hydrocarbons react with oxygen to produce carbon dioxide. Calcium carbonate decomposes to produce carbon dioxide.
5 (a) (i)
Complete each chemical equation by writing the formula of the other product. CH4 +
2O2
CaCO3
2 ............... ..........
+
+
CO2
CO2
(2 marks)
5 (a) (ii) Hydrocarbons and calcium carbonate contain locked up carbon dioxide. What is locked up carbon dioxide? ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks)
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11 5 (b)
Do not write outside the box
Graph 1 shows how the percentage of carbon dioxide in the atmosphere changed in the last 4500 million years. Graph 1 100 90 80 70
Percentage 60 (%) of CO2 50 in the atmosphere 40 30 20 0.03%
10 0 4500
4000
3500
3000 2500 2000 1500 Time in millions of years ago
1000
500
0
Use information from Graph 1 to answer these questions. 5 (b) (i)
Describe how the percentage of carbon dioxide has changed in the last 4500 million years. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks)
5 (b) (ii) Give two reasons why the percentage of carbon dioxide has changed. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) Question 5 continues on the next page Turn over 8/30 (11)
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Do not write outside the box
Graph 2 shows how the percentage of carbon dioxide in the atmosphere changed in the last 250 years. Graph 2 0.05
0.04
Percentage (%) of CO2 in the atmosphere
0.03
0.02
0.01
0.00 250
200
150 100 Time in years ago
50
0
Should we be concerned about this change in the percentage of carbon dioxide? Explain your answer. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks)
____ 10
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