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CHEMISTRY CBSE CLASS X

Ethanol / Ethyl Alcohol (C₂H₅OH )

Physical  properties :-

1. Colourless liquid having pleasant smell and burning taste .
2. Volatile liquid having low boiling point .
3. Lighter than water so it is soluble. Solubility of ethanol in water is due ot the presence of hydroxyl group in it.
4. Does not contain any hydrogen ions – neutral compound.
5. No effect on litmus paper.

Chemical properties :-

1. Combustion :- It is highly inflammable liquid and catches fire easily and starts burning in air with a blue flame to form CO₂ and water vapour and releases lot of heat and light.
   
   C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat + light
   
   
   1. Since it burns with a clear flame giving lot of heat, it is used as a fuel.
   2. Used as an additive in petrol. It does not produce any poisonous gas like carbon monoxide .
   3. Produced on large scale from sugarcane crop. ( after crystallization of sugar from concentrated sugar cane juice , a thick, dark brown liquid called molasses is left behind. Ethanol is produced by fermentation of the cane sugar present in molasses)
2. Oxidation  :-  It means controlled combustion. When ethanol is heated with alkaline potassium permanganate solution , it gets oxidized to ethanoic  acid.
   
   CH₃CH₂OH     + 2O →   CH₃COOH  +  H₂O
   
   Ethanoic acid  is formed by the oxidation of ethanol by using a strong oxidizing agent.
   1. Oxidation of ethanol to ethanoic acid can also be done by using acidified potassium dichromate as the oxidizing agent ( in place of alkaline potassium permanganate) .
      
      
3. Reaction with sodium metal :-  Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas :
   
   2C₂H₅OH + 2Na  →  2 C₂H₅ONa +  H₂
   
   
4. Dehydration  :-  It means removal of water molecule from it.
   When ethanol is heated with excess of conc. H₂SO₄ ( dehydrating agent)it gets dehydrated to form ethene.
   CH₃- CHOH   →CH₂= CH₂   +  H₂O
   
   
5. Reaction with Ethanoic acid :-  Ethanol reacts with ethanoic acid on warming in the presence of a few drops of conc. H₂SO₄ to form a sweet smelling ester , ethyl  ethanoate .
   
   CH₃COOH + C₂H₅ OH → CH₃COOC₂H₅ + H₂O
   
   
   • The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification.  It takes place in the presence of a catalyst H₂SO₄.

USES OF ETHANOL -

1. Manufacture of paints, varnishes, medicines, perfumes, dyes, soaps and synthetic rubber.
2. Used as a solvent.
3. Used as a fuel.
4. Used in alcoholic drinks
5. Used as an antiseptic to sterilize wounds.

Submitted By Mrs. Kritika Bhola
Email Id : [email protected]