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CHEMISTRY CBSE CLASS X
Ethanol / Ethyl Alcohol (C2H5OH )
Physical properties :-
- Colourless liquid having pleasant smell and burning taste .
- Volatile liquid having low boiling point .
- Lighter than water so it is soluble. Solubility of ethanol in water is due ot the presence of hydroxyl group in it.
- Does not contain any hydrogen ions – neutral compound.
- No effect on litmus paper.
Chemical properties :-
- 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
- Since it burns with a clear flame giving lot of heat, it is used as a fuel.
- Used as an additive in petrol. It does not produce any poisonous gas like carbon monoxide .
- 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)
- 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.
- 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) .
- Reaction with sodium metal :- Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas :
2C2H5OH + 2Na → 2 C2H5ONa + H2
- 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
- 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 -
- Manufacture of paints, varnishes, medicines, perfumes, dyes, soaps and synthetic rubber.
- Used as a solvent.
- Used as a fuel.
- Used in alcoholic drinks
- Used as an antiseptic to sterilize wounds.
CBSE Important Questions Class X Chemistry By : Mrs. Kritika Bhola
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