Question

how ethanol is obtained using aqueous NaoH

Answer 1

Ethanol, C2H5OH, (also called Ethyl Alcohol) is an aliphatic alcohol. Except for alcoholic beverages, nearly all the ethanol used industrially is a mixture of 95% ethanol and 5% water, which is known simply as 95% alcohol. Although pure ethyl alcohol (known as absolute alcohol) is available, it is much more expensive and is used only when definitely required.
Preparation:
Ethanol is prepared as 95% alcohol (i.e. a 95% solution of ethanol in water) by distillation of the solution which results from the fermentation of sugars.
Manufacture:
There are two major industrial pathways to ethanol. Ethanol which is intended for industrial use is made by the first method, while ethanol intended for food use tends to be made by the second method.
Reaction of Ethene with Steam :Most of the ethanol used in industry is made, not by alcoholic fermentation, but by an addition reaction between ethene and steam.as shown below:
C2H4 + H2O ==> C2H5OH
​Alcoholic Fermentation :A solution of sucrose, to which yeast is added, is heated. An enzyme, invertase, which is present in yeast is added and this acts as a catalyst to convert the sucrose into glucose and fructose.
C12H22O11 + H2O  →  C6H12O6 + C6H12O6

The glucose, C6H12O6, and fructose, C6H12O6, formed are then converted into ethanol and carbon dioxide by another enzyme, zymase, which is also present in yeast.

C6H12O6  → C2H5OH + 2CO2.

The fermentation process takes three days and is carried out at a temperature between 250C and 300CThe ethanol is then obtained by fractional distillation.