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 quicklime (CaO) for a few hours and then refluxing and distilling it.

Methylated Spirit or Denatured Alcohol

In order to make the industrial alcohol unfit of drinking purposes, the rectified 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.