The atmosphere

• the atmosphere is made up of these gasses

  Nitrogen, oxygen, carbon dioxide, water vapour, noble gasses and impurities
• Nitrogen 


  Nitrogen is a diatomic molecule which is 78% abundent in the atmosphere and is inert since the each atom is sharing 3 electrons with another nitrogen atom forming a nitrogen-nitrogen bond
• Oxygen


  is 20.8% abundant in the atmosphere and is the reactive part of the atmosphere since it supports combustion
• carbon dioxide

  is a compound composed of one carbon atom and two oxygen atoms. each oxygen is sharing two electrons. carbon dioxide is 0.03-0.04% abundant in the atmosphere. Carbon dioxide is produced during respiration and combustion
• Water 


  Is a compound of two hydrogen atoms and one oxygen atom, each hydrogen atom is sharing one electron with oxygen. Water vapor is a variable or has a variable composition in the atmosphere and depends on humidity.
• Noble gasses


  All group 8 elements are noble gasses. They occupy 1% of the atmosphere and they are unreactive since they are stable.
• Impurities


  They vary depending on the location. Impurities can be nitrogen dioxide or sulfur dioxide. Composition and abunance depends on location.
• To identify for carbon dioxide, bubble carbon dioxide on lie water, calcium hydroxide ( CA(OH)2) and it should turn milky white


  CA(OH)2 (aq)+ CO2 (g) --> CACO3 (s) + H2O (l)
• To test for oxygen, it relights a glowing splint
• To test for water, white anhydrous copper (II) sulfate, in contact with water changes to blue hydrated copper (II) sulfate 


  CUSO4 (s) +5H2O (l) --> CUSO4 . 5H2O (l)
• To test for water, Blue anhydrous Colbat (II) chloride, on contact with water, changes to pink hydrated Colbat (II) chloride 


  COCL2 (s) + 6H2O (l) --> COCL2 . 6H2O (s)
• Complete combustion is when the fuel finds enough oxygen to burn and only produces carbon dioxide. 


  The flame produced is Non luminus, strong, very hot
• In incomplete combustion, the fuel will not find enough oxygen to burn in and produce carbon monoxide and even carbon (soot)


  The flame produced is luminus (yellow), wavy and not very hot
• Rusting. When iron reacts with oxygen in the pressure of water vapor produced iron (III) oxide (Fe2O3) also known as rust. Unlike other oxides, iron (III) oxide dusts off its surfaces 


  4Fe (s) + 3O2 (g) --> 2Fe2O3 (s) Brownish solid rust.
• Methods to prevent rusting are:

  Painting or spraying, oiling or greasing, Galvenizing (dipping the whole structure in molten zinc), Electroplating (Coating the iron structure in a precious metal using electricity), and Sacrificial arode (attaching magnesium so it gets eroded instead)
• boiling point of nitrogen is -190 degrees celsius
• One simple method to determine the % of oxygen in air is to use two 100cm3 gas syringes connected on either side of a piece of heat resistant silica tubing containing excess granules of copper . ordinary glass tubing would melt
• one syringe is empty and the other is filled with exactly 100cm3 of air

  The silica tube/copper is strongly heated with a hot flame bunsen burner and the gas syringes are moved to and fro to pass the air over the hot copper so all the air comes into contact with it
• equation for copper oxygen %

  2CU (s) + O2 (g) --> 2CUO (s)
• A pollutant is a substance that normally dosen't exist in the atmosphere
• Sulfur dioxide is an impurity. it is present in diesel oil and during combustion. when SO2 comes out of the exhaust pipe, it reacts with water vapor t produce sulfurous acid(H2SO3). Sulfuric acid will produce 


  H2O (l) + SO2 (g) --> H2SO3 (aq)
• Acid rain reduces soil PH and kills plants, which reduces biodiversity. Normal rain has a PH of 5-6 but acid rain has a PH of 2-3. acid rain causes plant roots to poorly absorb nutrients from the soil.
• Acid rain causes ecosystem deyreration because large water bodies such as lakes have a narrow pH change. Acid rain lowers the pH of these water bodies causing aquatic organisms to die leading to ecosystem destruction.
• Acid rain causes corrosion of limestone buildings leading to buildings becoming weak and corrupted.
• Another impurity is nitrogen dioxide. In the hot parts of a car engine there is enough heat for the nitrogen molecule to split and nitrogen reacts with oxygen to form nitrogen dioxide. 


  Oxides of nitrogen will also cause photochemical smog
• The effects of photochemical smog are that the oxides of nitrogen will react with water and absorb solar radiation. In doing so breakdown producing highly toxic substances


  These substances cause irritation to eyes and causing difficulty in breathing
• carbon dioxide is also an impurity. The amount of CO2 produced during the burning of fossil fuels have significantly increased the consentration of CO2 in the atmosphere 


  Carbon dioxide absorbs solar radiation and reflects it back to the earths surface. This causes the greenhouse effect.
• The greenhouse effect is causing global warming and due to this the polar ice cops are melting at a faster rate and also causing the sea level to rise.


  The concentration of CO2 is leading to climate change and this is also causing habitual destruction and leads to extinction of species
• Carbon monoxide also being an impurity ,is a colorless, oderless gas and is insoluble in water. the smallest amount of carbon monoxide can be deadly (1%)


  CO binds permanently to hemoglobin, producing carboxy hemoglobin. This will reduce the carrying capacity of red blood cells to supply oxygen leading to insufficient transportation
• Catlytic converters are structures installed in the exhaust system in a car. It is made of expensive metals such as platinum (pt) , rhodium (rh), and pauadium (pd)


  Being expensive, the converter is made up of a honeycomb structure to reduce the amount of metal used and used to increase efficiency. The converter is made up from a reductive part and an oxidative part
• Reductive catylitic converters reduce nitrogen monoxide and nitrogen dioxide to oxygen and nitrogen gasses

  2NO2 --> N2 + 2O2

  2NO --> N2 + O2
• In oxidative catylytic converters, unburnt fuel will react to form carbon dioxide and water. Carbon monoxide is converted to carbon dioxide 


  2CO + O2 --> 2CO2

  2C8H18 + 25O2 --> 16CO2 + 18H2O (Octone)
• Note- Catylitic converters can't be used in diesel engines since diesel engines produce small partiuclate matter (pm) that deposits on the converter, poisoning it in the process
• Chloroflouro carbon are a group of compounds which were used exteneivley in aerosol propelants and refrigerant gasses 


  CFC'S are very stable when they are present in the troposphere (The atmosphere which is 10km above sea level)
• CFC'S become reactive at the stratosphere (between 10-15km above sea level) by absorbing ultra violent light producing a toxic and harmful substance. These substances attack the ozone layer causing deplation.


  Ozone is a protective layer that protects the earth from harmful uv radiation
• Some effects of ozone depletions are higher risk of skin cancer and the bleaching of coral reefs