Explain the preparation of alkenes from alcohols by acidic dehydration.

(N/A) Alcohols ($C_{n}H_{2n+1}OH$,where $n \geq 2$) react with concentrated mineral acids such as $H_{2}SO_{4}$ or $H_{3}PO_{4}$ at high temperatures to undergo dehydration,resulting in the formation of alkenes.
Reaction Mechanism:
In this reaction,the $-OH$ group from the $\alpha$-carbon and a hydrogen atom from the $\beta$-carbon are removed as a water molecule $(H_{2}O)$. This leads to the formation of a $\pi$-bond between the $\alpha$ and $\beta$-carbons. Because this process involves the elimination of a water molecule,it is called acidic dehydration. It is also known as a $\beta$-elimination reaction.
General Reaction:
$CH_{3}-CH_{2}-OH \xrightarrow[\Delta, 443 \ K]{Conc. \ H_{2}SO_{4} \ / \ H_{3}PO_{4}} CH_{2}=CH_{2} + H_{2}O$