OXYGEN

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  • OXYGEN
    • % OF OXYGEN IN THE AIR
      • Copper Experiment
        • Method
          • 1.100cm3 of air is put in one syringe
          • 2. The syringe plungers are moved in and out so that all of the air is passed over the hot copper
        • Observations
          • Air is passes backwards and forwards across the hot copper and the volume of air decreases
            • This is because when copper is heated, it reacts with oxygen in the air to make copper (II) oxide - so the reaction uses up oxygen
              • Therefore the volume of air decreases by about 20% (% of oxygen in the air)
      • Iron or Phosphorus Experiment
        • Method
          • 1. Soak some iron wool in acetic acid and push the wool into a test tube
            • CATALYST = Acetic acid
          • 2. Invert the tube into a beaker of water
        • Observations
          • Over time the level of water in the test tube will rise
            • This is because the iron reacts with the oxygen in the air to make iron oxide
              • The water rises fill the spacto e the oxygen took up
        • % of oxygen = vol of air used // vol of    air at start    x100
    • MAKING OXYGEN
      • Pure oxygen can be made from hydrogen peroxide (H2O2)
      • Hydrogen peroxide will decompose into water and oxygen
        • The decomposition is really slow but the rate of the reaction can be increased with a catalyst
          • CATALYST = Manganese oxide (MnO2)
      • Collection?
        • Over water
        • Using a gas syringe
    • REACTIONS WITH OXYGEN IN AIR
      • MAGNESIUM
        • WHAT'S PRODUCED? a white powder called magnesium oxide
        • FLAME? bright white
        • Magnesium oxide is slightly alkaline (when dissolved in water)
      • SULFUR
        • WHAT'S PRODUCED? sulfur dioxide gas
        • FLAME?   pale blue
        • Sulfur dioxide is acidic (when dissolved in water)
        • burns in oxygen or air
      • CARBON
        • FLAME? yellow/orange
        • WHAT'S PRODUCED? carbon dioxide gas
        • Carbon dioxide is slightly acidic (when dissolved in water)
        • burns in air if its very strongly heated

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