Question

The products formed when ethanol vapours passed over alumina at 653 K is :
a.) alkene
b.) alkane
c.) alcohol
d.) phenol

Answer 1

Hint: When ethanol vapours are passed over alumina at 653 K temperature then the dehydration reaction takes place. The water is removed giving ethene. The reaction can be written as -
$C{H}_{3}C{H}_{2}OH\stackrel{Alumina,653K}{\to }C{H}_2=C{H}_2$

Complete Solution :
The ethanol is an alcohol. When ethanol vapours are passed over alumina at 653 K temperature then the dehydration reaction takes place. As a result, the water is removed and ethene is formed as a product. The reaction can be written as -
$C{H}_{3}C{H}_{2}OH\stackrel{Alumina,653K}{\to }C{H}_2=C{H}_2$
The ethene is an alkene.
So, the correct answer is “Option A”.

Additional Information:
The ethanol is two-carbon alcohol. It is commonly called spirit or drinking alcohol. It is volatile and is flammable. It is used as antiseptic. It is used in medicinal wipes, hand sanitizers. Its consumption can increase the release of acid in the stomach. It can also be used as engine fuel or as a fuel additive. It is also used as rocket fuel. It has wide use in industries. It is used as a precursor for the formation of ethyl halides, ethyl esters, diethyl ether and acetic acid etc.

Note: It must be noted that the temperature is high. If the temperature would have been less i.e. approximately 523 K, then there would be dimerization of alcohol. This would have given diethyl ether as the product. But the heating is at a large temperature, so the product is an alkene.