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manufacture of ethanol by passing steam over phosp

A mixture of ethene and steam is passed over phosphoric acid catalyst at a temperature of 300 degrees c and 60-70 atm of pressure.

C2H4(G) + H20(g) GOES TO C2H5OH(g)

 Ethanol is condensed as a liquid.Ethene required for this reaction is obtained by crude oil.

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manufacrure of ethanol by fermentation

Dissolve sugar and starch in water and add yeast.

Leave mixture to ferment at 25-40 degrees C for several days in absence of air.

Filter off the excess yeast to obtain a dilute solution of ethanol.

If the ethanol content in the mixture rises to around 15% , yeast is killed(only if more concentrated solution ; the mixture is fractionally distilled.

C6H12O6(AQ)GOES TO 2C2H5OH(AQ) + 2CO2(G)

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Factors relevant to the fermentation of ethane

  • Raw materials= renewable resources e.g. sugar cane.
  • Type of process= batch process.
  • Rate of reaction = very slow, takes several days for each batch.
  • quality of product=produces a dilute solution of ethanol that needs further processing (if pure ethanol is required)
  • reaction conditions-low temperatures required.
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Dyhydration of ethanol to ethene using aluminium o

Pass ethanol vapour over hot aluminium oxide, this acts as a catalyst for the reaction.

This reaction can be used to maufacture ethene for the production of poly(ethene).

c2h5oh(g) goes to c2h4(g) + h2o(g)

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Factors relevant to the dehydration of ethene


  • Raw materials= non-renewable resources,crude oil will run out.
  • type of process = continous process
  • rate of reaction = fast
  • quality of product= produces pure ethanol.
  • Reaction conditions= high temperatures and pressure required , this increases cost.


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How are long chain alkanes converterted to shorter

By catalytic cracking , silica or alumina catalyst and 600 -700 degrees C is ised to turn long hydrocarbons inro short chain hyrdorcarbons.

During this a mixture of alkenes and alkanes are fromed during catalytic cracking.

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alkEnes and alkAnes


general formula =Cnh2n

Have carbon caron double bonds.


  • eg
  • ethene= c2h4
  • propene c3h6

When bromine is shaken with ethene , ethene will be decolourised.


general formula cnh2n+2

don't have carbon carbon double bonds

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