C1

C1

1. The Evolution of the Atmosphere

   • Phase 1
     • 1. The earths surface was moulton,so the atmosphere boiled away
     • 2. The earth cooled down a bit - thin crust formed
     • 3. Volcanoes erupted and gave out gases including CO2, water vapour and nitrogen (atmosphere - formed)
     • 4. Oceans where formed when the water condensed when the Earth cooled
   • Phase 2
     • 1. Green plants evolved
     • 2. CO dissolved into the oceans, plants took in the CO2 and produced Oxygen through photosynthesis
   • Phase 3
     • 1. The oxygen levels increased and killed off organisms that could not evolve - created more complex organisms

2. The Atmosphere today

   • Nitrogen -78% Oxygen- 21% Argon-1%
   • Human activicty adds pollutats to the atmosphere
     • Directly harmful
       • e.g - carbon monoxide which creates flu like symptoms and eventually death
     • Indirectly harmful
       • e.g- acid rain - kills fish - people eat

3. Chemical Reactions

   • Diagrams can represent molecules
   • Chemical reactions happen when Atoms are Rearranged
     • Chemical reactions involve atoms changing places
     • No atoms disappear
       • No mass is lost
       • The mass of the reactants = mass of products

4. Fossil Fuels

   • Hydrocarbons
     • Most fuels are hydrocarbons - carbon+hydrogen=hydrocarbons (a compound)
     • Many hydrocarbons are fossil fuels
   • Burning fuels
     • e.g- when hydrocarbon burns, hydrocarbon atoms in the fuel combine with oxygen atoms in the air to make hydrogen oxide
     • Reaction where oxygen is added is an oxidation reaction e.g combustion
     • Reaction where oxygen is lost are called reduction reactions
     • Oxygen is needed to burn hydrocarbons - can come from air or pure oxygen
       • Hydrocarbons burn more rapidly in pure oxygen than they do in air

5. Air Pollution

   • Carbon
     • Carbon Dioxide
       • Stays into the atmosphere till removed
       • Removed naturally by photosynthesis
       • Increases Carbon Dioxide increases the greenhouse effect, warming the earth
     • Carbon Monoxide
       • The molecule has 1 oxygen atom
       • Produced by incomplete burning - not enough oxygen when fuels burn
       • Poisonous
     • Particulate Carbon
       • Produced when fuels burn incompletely
       • When they escape to the atmosphere they float around and fall to the ground eventually as soot
   • Sulfur
     • Sulfur pollution comes from impurities in fuels
       • fuels contain impurities from when they are extracted
         • Most are harmless but some have sulfur
       • When the fuel is burned sulfur burns too
         • Sulfur + oxygen = sulfur dioxide
     • Sulfur pollution - Acid Rain
       • 1. Stays in atmosphere
       • 2. Leaves in the form of acid rain
       • 3. Sulfur dioxide reacts with cloud moisture - dilute sulfuric acid is formed
       • 4. Falls as acid rain
       • 5. Causes lakes to become acidic - kills animals & plants, damages buildings and status and kills trees
   • Nitrogen
     • Nitrogen pollution comes from nitrogen in the air when a fuel is burnt
       • 1. fossil fuels burn at high temps so nearby atoms in the air react with each other
       • 2. Nitrogen + oxygen = Nitrogen Oxides (nitrogen monoxide/dioxide)
       • 3. Happens in car engines
       • 4. Put into the atmosphere
     • Nitrogen monoxide
       • NO
       • Forms when nitrogen and oxygen in the air are exposed to high temps
     • Nitrogen Dioxide
       • NO₂
       • Formed when Nitrogen monoxide reacts with more oxygen

6. Reducing Pollution

   • Power Stations
     • Use less electricity
       • Less fossil fuels - less pollution
     • 1.Take sulfur out from natural gas and fuel oil - not so much sulfur dioxide
     • 2.When coal is burnt, sulfur dioxide and particulates can be removed from flue (chimney) gases
       • Sulfuric acid can be removed from flue gases by reacting with alkali - wet scrubbing
         • 1. Seawater - sulfur dioxide dissolved in seawater, produces C02, H20 and dissolved sulfate
         • 2. Alkaline Slurry - Slurry is sprayed onto the gases and the sulfur dioxide reacts with calcium oxide. Calcium sulfate is formed.
   • Cars
     • More efficient engines
     • Catalytic converters, convert nitrogen monoxide into nitrogen and oxygen . Reduction reaction - nitrogen loses oxygen
       • Also convert toxic gas Carbon Monoxide into C02 by adding oxygen - oxidation reaction
     • There's a legal limit on how much polluting emissions can be given out from cars (MOT checks)
     • Use car less
     • Other options to power cars other than fuel
       • Burn biofuels
       • Electric batteries

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