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Air and Water - Coggle Diagram

- - - - very stable, requires a lot of energy to break
        
        use to flush through food packages to remove oxygen and keep the food fresh ( O2 helps decay )
      - liquid N2
        
        freeze food quickly
    - - Oxygen percentage measurement
        
        apparatus
        
        a tube of hard glass is connected to 2 glass syringes
        
        the tube is packed with small pieced of copper wire
        
        Syringe A contains 100cm3 of air, Syringe B is empty
        
        methods
        
        heat the tube with a Bunsen burner. Push A and B their both plungers repetitively, oxygen in air reacts with copper
        
        stop heating after 3 minutes, allow it to cool, push all the gas into 1 syringe and measure the volume
        
        repeat until the volume of the gas remains steady, note the final volume
      - Uses of Oxygen
        
        Respiration
        
        glucose + oxygen ------> carbon dioxide + water + energy
        
        C6H12O6 + O2 ------->CO2 + H2O
        
        Combustion ( fuels combustion )
        
        cutting and welding metals ( O2 + acetylene gas C2H2
    - - Ar
        
        protective gas in tungsten light bulbs / welded metals ( to provide an inert atmosphere )
      - Ne
        
        advertising signs (glows red, mix with other gases to change colors)
      - He
        
        fill balloons/airships (much lighter than air, will not catch fire)
      - Xe
        
        car headlamps, hospital operating rooms
  - - - 1) Air is filtered to remove dust particles
      - 2) Air is cooled until water vapor condenses to water, CO2 and other pollutants are removed by passing over beds of absorbent beads
      - 3) Air is compressed and cooled by recycling cold air
      - 4) Cold air is cooled again by passing through a jet into a larger space
      - 5) Liquid air is pumped into fractionating column, where it is slowly warmed up. N2 will be the first collected
- - - - petroleum
      - natural gas
      - coal
  - - - source of CO: incomplete combustion of fossil fuels
      - Problems of CO
        
        1) can combine with haemoglobin in blood
        
        2) decrease the capacity of blood cell to carry O2 around the body, the level of O2 in blood will decrease (the death is caused by oxygen starvation)
    - - N2 + O2 ------>2NO (High temperature/Pressure)
      - 2NO + O2 ------> 2NO2
        
        NO2 + H2O ----->HNO3 + HNO2
        
        nitric acid (HNO3) and nitrous acid (HNO2) are corrosive, therefore will cause acid rain
      - Problems of NOx
        
        1) cause acid rain
        
        2) cause respiratory problems
  - - - H2SO4 ( sulfuric acid )------> acid rain
    - - cause acid rain
        
        attack limestone ( CaCO3 ) and marble in buildings
        
        kill fish and trees
      - irritate eyes & throat, cause respiratory problems
    - - SO2 +Ca(OH)2 ------>CaSO3 + H2O
      - 2CaSO3 + O2 + H2O --------> 2CaSO4-2H2O
        
        2CaSO4-2H2O (hydrated calcium sulfate)
  - - - Lead damages children's brains
      - Lead damages kidneys and nervous system
- - - - CO is oxidised
    - - Catalyst: Pt
        
        NO is reduced
- - - - CuSO4----->white powder
      - CuSO4-5H2O----->blue crystal
    - - turns to pink
    - - Pure: b.p. 100 celcius
        m.p. 0 celcius
      - Impure: b.p. will be higher
        m.p. will be lower