Presentation on theme: "13/01/2014 Air Quality W Richards The Weald School (OCR 21 st Century)"— Presentation transcript:
13/01/2014 Air Quality W Richards The Weald School (OCR 21 st Century)
13/01/2014 Section C1.1 – Our air
13/01/2014 The Earths Atmosphere Carbon dioxide, water vapourOxygenNitrogenNoble gases Present day atmosphere contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO 2
13/01/2014Air Air is a mixture of different gases consisting of small molecules with large spaces between them:
13/01/ Billion years3 Billion years2 Billion years1 Billion yearsPresent day Evolution of the Earth s Atmosphere Carbon dioxide MethaneAmmoniaOxygenNitrogenOthers Present day atmosphere contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO 2
13/01/ Billion years3 Billion years2 Billion years1 Billion yearsPresent day Evolution of the Earth s Atmosphere Volcanic activity releases CO 2, methane, ammonia and water vapour into the atmosphere. The water vapour condenses to form oceans. Some of the oxygen is converted into ozone. The ozone layer blocks out harmful ultra-violet rays which allows for the development of new life. Green plants evolve which take in CO 2 and give out oxygen. Carbon from CO 2 becomes locked up in sedimentary rocks as carbonates and fossil fuels. Methane and ammonia react with the oxygen and nitrogen is released.
13/01/2014 Carbon dioxide in the atmosphere The amount of CO 2 in the atmosphere is affected by 3 things: 1) Geological activity moves carbonate rocks deep into the Earth and they release ______ _______ into the atmosphere during volcanic activity. 2) When fossil fuels are burned the carbon contained in them reacts with _____ to form CO 2. 3) Increased CO 2 in the atmosphere causes a reaction between it and _______. These reactions do not remove ALL of the new CO 2 so the greenhouse effect is still getting _______! Words – oxygen, seawater, carbon dioxide, worse
13/01/2014Pollution What happens to pollution? Carbon dioxide causes global warming but some of it can be removed by plants (photosynthesis) or reactions with seawater. Sulfur dioxide and nitrogen dioxide cause acid rain which damages trees and buildings. Particulates (like in smog) can make buildings dirty and worsen breathing difficulties.
13/01/2014Pollution Humans pollute the Earth in a number of ways: PollutantHarmful to...Why? Carbon dioxideEnvironment Nitrogen oxidesEnvironment + humans Sulfur dioxideEnvironment Particulates (e.g. Smoke) Environment + humans Carbon monoxideHumans A greenhouse gas that causes global warming Causes acid rain and makes asthma/breathing problems worse Causes acid rain Makes buildings dirty and makes asthma worse Displaces oxygen in red blood cells that can result in death
13/01/2014 Section C1.2 – Pollution
13/01/2014Fuels Fuels are substances that can be used to release useful amounts of energy when they burn, e.g. Oil Gas Wood Coal These fuels are called fossil fuels and are described as being non-renewable. The main element in these fuels is Carbon.
13/01/2014 Burning Hydrocarbons Burning hydrocarbons will produce water, carbon dioxide and energy: C H H H H O O O O O H H O H H C O O MethaneOxygen+Water+Carbon dioxide In this reaction the hydrocarbon is oxidised (oxidised means that oxygen has been added and its the opposite of reduced). Oil, petrol and diesel are all examples of HYDROCARBONS. A hydrocarbon is a compound made up of carbon and hydrogen.
13/01/2014 More information on oxygen Fuels need oxygen to burn. The more oxygen they have, the quicker they will burn. This is the principle behind oxy- acetylene torches:
13/01/2014 Other products of burning fuels Sulphur dioxide: Nitrogen monoxide: Nitrogen monoxide can be further oxidised to make nitrogen dioxide (Nitrogen monoxide and dioxide are jointly referred to as NOx): S O O Sulphur dioxide S O O SulphurOxygen+ Nitrogen monoxide N O N O Oxygen+ O O Nitrogen N N O O Oxygen+ Nitrogen monoxide N O N O Nitrogen dioxide N O O N O O
13/01/2014 Conservation of mass in reactions In any reaction the total mass of products is the same as the total mass of the reactants Example 1 – Magnesium oxide and hydrochloric acid Mg O H Cl Mg Cl H H O H 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms Also 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms C H H H H O O O O O H H O H H C O O Example 2 – Burning methane
13/01/2014 Incomplete Combustion As well as producing carbon monoxide, incomplete combustion can also produce soot: Little oxygen: CC H H H H Methane O O Oxygen+ O H H O H H Water+Carbon Soot
13/01/2014 Burning Fossil Fuels Burning fossil fuels like oil and coal causes pollution. Oil contains carbon: C H H H H O O O O O H H O H H C O O Carbon dioxide is a greenhouse gas – it helps cause global warming Coal contains carbon, sulfur and other particles: sulfur + oxygen sulfur dioxide Sulfur dioxide causes acid rain. Other particles can cause global dimming – sunlight is absorbed by the particles in the atmosphere.
13/01/2014 Summary of pollutants C Carbon C O O Carbon dioxide Nitrogen monoxide N O Nitrogen dioxide O N O S O O Sulfur dioxide O H H Water C Carbon monoxide O Each of the following chemicals is a product of burning fossil fuels. For each one summarise how it is made and what harm it causes:
13/01/2014 C1.3 Improving Air Quality
13/01/2014 Removing Pollution There are many ways pollution can be reduced: Use less electricity/central heating Remove toxic chemicals before or after they are burnt Use alternative energy sources, e.g. wind power
13/01/2014 Removing Sulfur 13/01/2014 Sulfur dioxide is clearly bad for the environment so its a good idea to remove as much sulfur as possible: Vehicles can remove sulfur from fuels before they are burned. Power stations can remove sulfur dioxide from waste gases after combustion.
13/01/2014 Wet Scrubbing Wet scrubbing is a term used to describe the removal of sulfur dioxide and other particles using seawater or an alkaline spray: Step 1 – the dirty gas is fed in through the top. Step 2 – the scrubbing liquid (seawater or alkaline spray) is fed in through the side. Step 3 – the mixture is fed into a cyclone area where the slurry is collected at the bottom of the device.
13/01/2014 Reducing Pollution from vehicles A number of suggestions: 1) Buy a new, smaller, more efficient car 2) Use legal limits (e.g. An MOT) to enforce lower emissions 3) Use low sulfur fuels or convert your car to run on biodiesel 4) Make sure your car has a catalytic converter: 5) Use the train or a bus! Carbon monoxide + oxygen carbon dioxide Nitrogen monoxide + carbon monoxide nitrogen + carbon monoxide
13/01/2014 Alternative Fuels Car makers are currently researching two alternatives for petrol and diesel-powered cars. What are the advantages and disadvantages of each? 1)Electric cars Advantages: Disadvantages: 2)Biofuel cars Advantages: Disadvantages:
13/01/2014 Making choices about pollution Choices concerning fighting pollution can be made on many levels: 1)International e.g. The Kyoto protocol in )National e.g. Car tax system, subsidies for greener technology 3)Local e.g. Recycling schemes, transport, congestion charges 4)Personal e.g. Recycling, individual travel, reducing energy usage in the home etc