Please enable JavaScript.

Coggle requires JavaScript to display documents.

2018 O'LEVEL PURE CHEMISTRY[SYLLABUS:6092]CHAPTER 19:AMMONIA Pure…

- - - - Fractional Distillation of liquid air.
    - - Cracking of petroleum(Hydrocarbon,Crude oil).
  - - - Reversible reaction
        
        Backward and forward process occurring simultaneously.
        
        Yield not 100% as some NH3(g) decompose back to N2 and H2.
        
        Dynamic equilibrium.
        
        Rate of forward reaction=Rate of backward reaction.
        
        Reaction mixture contains a fixed proportion of reactants and products of a reversible reaction at specific reaction conditions.
  - - - (1)NH3 gas is condensed into liquid in order to be separated from excess N2 and H2.
        (2)NH3 condenses most easily because it has the highest boiling point compared to N2 and H2.
        (3)Excess N2 and H2 gas are recycled to make more NH3 to increase the yield of ammonia.
      - (a)N2 and H2 are mixed in the proportion 1:3.
        (b)The mixture of gasses is compressed to 200 atm.
        (c)The gasses are passed over finely divided iron at 450 ℃ and 200 atm. Iron acts as a catalyst in the reaction.The reaction is exothermic.
        (d)Only about 10-15 % of the nitrogen and hydrogen combine to form ammonia.A mixture of ammonia,nitrogen and hydrogen leaves the converter.
        (e)The mixture of gasses is cooled.Ammonia condenses to form liquid ammonia.
        (f)Unreacted N2 and H2 are pumped back into the converter for further reaction(Recycled).
  - - - Higher ammonia yield
      - High cost of maintenance
    - - Higher ammonia yield
      - Slower rate of reaction