Question

What is the action of the following reagents on ethanoic acid?
$P_2{O}_5$, heat.

Answer 1

When ethanoic acid (acetic acid) is heated with $P_2{O}_5$, acetic anhdride is obtained. A molecule of water is eliminated from two molecules of ethanoic acid.

$\underset{\text{ethanoic acid}}{2C{H}_3-COOH}\underset{\Delta }{\overset{P_2{O}_5}{\to }}\underset{\text{Acetic anhydride}}{(C{H}_3-CO-{)}_{2}O}+H_{2}O$