Question

On addition of small amount of $KMn{O}_4$ to $conc.H_{2}S{O}_4$, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following.

• A. $M{n}_2{O}_7$
• B. $Mn{O}_2$
• C. $MnS{O}_4$
• D. $M{n}_2{O}_3$

Answer 1

The correct option is A $M{n}_2{O}_7$

${Mn}_2{O}_7$ arises as a dark green oil by the addition of concentrated $H_{2}S{O}_4$ to $KMn{O}_4$. The reaction initially produces permanganic acid, $HMn{O}_4$ (structurally, $HOMn{O}_3$), which is dehydrated by cold sulfuric acid to form its anhydride, ${Mn}_2{O}_7$.

$2KMn{O}_4+2H_{2}S{O}_4⟶{Mn}_2{O}_7+H_{2}O+2KHS{O}_4$

${Mn}_2{O}_7$ is highly explosive in nature.