Industrial Inorganic Chemistry

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Industrial Inorganic Chemistry

• By Tharmini Tharmakulasingam

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Introduction

• Inorganic compounds are compounds which are
  not made up of only carbon and hydrogen( organic
  compounds).
• Kinetics and equilibrium are important
  factors in industry in order for a good economy
  which is obtained my maximising
• Yield
• The speed of the reactions
• And minimise
• The cost
• Pollution of the environment
• High pressure is expensive to achieve and
  maintain as it requires allot of energy for the
  compression of these gasses and also for the
  pipes which need to be able to withstand the high
  pressure.

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Ammonia, NH3

• The process which is used to manufacture Ammonium
  is called the Haber process. This process is
  the synthesis of ammonium from nitrogen and
  hydrogen, in which the equilibrium is
  established.
• 
  ?H -92.4 KJ
  mol ¹
• As formation of ammonia is exothermic and
  produces fewer molecules the position of the
  equilibrium is more favoured for a lower
  temperature but higher pressure.
• The optimum conditions for the Haber Process
  is
• Optimum pressure400 atmospheres
• Optimum Temperature 673 Kelvin (400-450c)

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The Raw Materials

• The hydrogen is obtained from natural gas, which
  contain methane or naphtha fraction of petroleum,
  a hydrocarbon mixture by reaction with steam in
  the precence of a nickel catalyst.
• Carbon monoxide will poison the catalyst and
  therefore must be removed from the gases before
  passing through the catalyst. Air is injected
  into this mixture and, by a series of reactions,
  nitrogen and hydrogen are produced in a 13
  ratio, as required by the process, the carbon
  monoxide, now oxidised to carbon dioxide, is
  removed from the system.
• Although natural gas is readily available at the
  moment, it will not always be this way. The
  alternative fossil fuel is coal, which was
  previously used (in the form of coke), could be
  used again, but this is also a finite resource.

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Conditions used in the Haber Process

• Synthesis gas, which is a mixture of nitrogen and
  hydrogen in a molar ratio of 13, is compressed
  to a pressure of 200- 250 atm and heated to a
  temperature of 400C.
• The gases are passed over a iron catalyst
  promoted with some potassium hydroxide). About
  15 of the nitrogen is converted into ammonium in
  the process.
• The gases leaving the reactor are cooled and the
  ammonia liquefies.
• The unreacted nitrogen and hydrogen are mixed
  with more synthesis gas and recycled through the
  plant.

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Uses of Ammonia

• One use of ammonium is to make fertilisers. About
  80 of the ammonia produced is converted into
  fertilisers. For example
• The salt, ammonium nitrate, is made by the
  reaction between ammonia (a base) and nitric
  acid. Ammonium nitrite is used as a fertiliser
  and contains about 35 nitrogen.
• About 10 of the ammonia manufactured is
  converted into polymer fibres, such as polyamide
  (nylon).
• A small amount of ammonium is used domestically
  in products such as window cleaning liquids.
• 5 of ammonium is also used to make explosives.

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Nitric acid, HNO3

• Ammonium is oxidised by the oxygen in the air to
  nitrogen monoxide, NO, and then to nitrogen
  dioxide, NO2 . Nitrogen dioxide is finally
  oxidised by nitric acid by air and water. In
  three steps
• Catalytic Oxidation
• Cooling
• Absorption
• Uses of Nitric Acid
• Nitric acid is used in the manufacturer of
• The fertiliser ammonium nitrate
• HNO3 NH3 ? NH4NO3
• Explosives such as TNT and dynamite
• Dyes

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Sulphuric Acid

• The process by which Sulphuric acid is
  manufactured is called the contact process.
• Stage 1 Production of Sulphur dioxide
• Sulphur dioxide is made by the combustion of
  sulphur. Liquid Sulphur is sprayed into a
  combustion chamber with excess dry air.
• S (l) O2 (g) ? SO2 (g) ?H?r -190
  mol¹
• Stage 2 Conversions of Sulphur dioxide to
  Sulphur trioxide
• SO2 (g) ½ O2 (g) ----- gt Reversible reactiongt
  SO3 (g) ?H?r -98kJ mol¹
• Important points about this reaction are that
• It is reversible
• It is too slow at room temperature to be useful
• It is exothermic from left to right
• There are 1 ½ moles of gas on the left and 1 mole
  on the right hand side of the equation.

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• Stage 2 Absorption of Sulphuric acid
• The gases from stage 2 contain a small amount of
  sulphur dioxide mixed with the sulphur trioxide
  and excess air. The sulphur trioxide cannot be
  absorbed directly into water because it would
  react with water vapour and produce a fog of
  sulphuric acid droplets. Instead, it is absorbed
  by the water in 98 sulphuric acid
• SO3 (g) H2O (in 98 H2SO4) ?H2SO4 (l)
• Uses of sulphuric acid
  
• Fertilisers
• Paints
• Soaps and detergents
• Man made fibres