Give preparation of Absolute Alcohol,

Give preparation of Absolute Alcohol,


1 Answers

askIITIians Expert
21 Points
15 years ago

Preparation of Absolute Alcohol:

Absolute alcohol is 100% ethanol. The rectified spirit (95.5% ethanol + 4.5% water) is a constant boiling mixture (Azetropic solution) and water cannot be removed by simple fractional distillation method.

In the laboratory absolute alcohol is prepared by keeping the rectified spirit in contact with calculated amount of quick lime (CaO) for a few hours and then refluxing and distilling it.

Methylated Spirit or Denatured Alcohol:

In order to make the industrial alcohol unit for drinking purposes, th erectified alcohol is denatured by adding various poisonous compounds like methanol, pyridine, acetone or petroleum naphtha, etc. This denatured spirit is 95% ethanol and 5% methanol. The methylated spirit is a mixture of 90% ethanol, 9% methanol and 1% other poisonous substances pyridine and acetone or petroleum oil.

Power Alcohol: It has been found that absolute ethyl alcohol mixed with petrol and benzene can be used as  a motor fuel. Alcohol thus used for generating power is called Powr alcohol. A mixture of 20% ethonol abd 80% gasoline is used in internal combustion engines to derive power. Since, alcohol it self, doesnot mix with petrol, therefore, a third solvent such benzene, ether or tetralin is used as a solvent.

Physical Properties:

  • Ethyl alcohol is a colorless liquid with a burning taste
  • It is inflammable and burns with a blue flame.
  • It boils at 78.10 C and has a specific gravity 0.789 at 200 C.
  • Unlike methyl alcohol, it is not a toxic liquid .
  • It mixes with water in all proportions.
  • Ethyl alcohol is a good solvent for oils, fats, resins etc.
  • When take internally ethyl alcohol is readily oxidised by the system

Chemical Properties:

Ethyl alcohol shows all the general characteristics of a monohydric (primary) alcohol. It is a neutral substance. It doesnot affect the pH of the water. It burns with blue flame in air or oxygen forming carbon dioxide and water.

C2H5OH + 3O2 2CO2 + 3H2O

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