Question

Reaction of solid $KMn{O}_4$ with conc. $H_{2}S{O}_4$ produces manganese heptoxide $(M{n}_2{O}_7)$ in

• A. solution state
• B. solid state
• C. fine powder
• D. none of these

Answer 1

Answer: (A)

$KMn{O}_4$ on treatment with conc. $H_{2}S{O}_4$ forms manganese heptoxide via permanganyl sulphate which decomposes explosively on heating
$2KMn{O}_4+3H_{2}S{O}_4\to 2KHS{O}_4+(Mn{O}_3{)}_{2}S{O}_4+2H_{2}O$
$(Mn{O}_3{)}_{2}S{O}_4+H_{2}O\to \underset{\text{Red-brown liquid}}{M{n}_2{O}_7}+H_{2}S{O}_4$
$M{n}_2{O}_7\to 2Mn{O}_2+\frac{3}{2}{O}_2$
$\therefore M{n}_2{O}_7$ so formed is a red-brown liquid