Question

What is the correct representation of reaction occurring when HCl is heated with $Mn{O}_2$ ?

• A. $Mn{O}_4^{-}+5C{l}^{-}+8H^{+}\to M{n}^{2+}+5C{l}^{-}+5H_{2}O$
• B. $Mn{O}_2+2C{l}^{-}+4H^{+}\to M{n}^{2+}+C{l}_2+2H_{2}O$
• C. $2Mn{O}_2+4C{l}^{-}+8H^{+}\to 2M{n}^{2+}+2C{l}_2+4H_{2}O$
• D. $Mn{O}_2+4HCl\to MnC{l}_4+C{l}_2+H_{2}O$

Answer 1

Answer: (B)

$Mn{O}_2+2C{l}^{-}+4H^{+}\to M{n}^{2+}+C{l}_2+2H_{2}O$

Reaction involved is:

$Mn{O}_2+HCl\to MnC{l}_2+C{l}_2+H_{2}O$

Assign the oxidation states we get:

$\stackrel{+4}{Mn}{O}_2+H\stackrel{-1}{Cl}\to \stackrel{+2}{Mn}C{l}_2+\stackrel{0}{C{l}_2}$

thus electron change in oxidation of Cl and reduction of Mn are same-2 electrons each

balance Cl

$\stackrel{+4}{Mn}{O}_2+4H\stackrel{-1}{Cl}\to \stackrel{+2}{Mn}C{l}_2+\stackrel{0}{C{l}_2}$

Balance O by adding $H_{2}O$

$\stackrel{+4}{Mn}{O}_2+4H\stackrel{-1}{Cl}\to \stackrel{+2}{Mn}C{l}_2+\stackrel{0}{C{l}_2}+2H_{2}O$

$\therefore$ balanced chemical reaction is:

$Mn{O}_2+4HCl\to MnC{l}_2+C{l}_2+2H_{2}O$
The reaction can be represented in the ionic form as:

$Mn{O}_2+4C{l}^{-}+4H^{+}\to M{n}^{2+}+2C{l}^{-}+C{l}_2+2H_{2}O$

OR

$Mn{O}_2+2C{l}^{-}+4H^{+}\to M{n}^{2+}+C{l}_2+2H_{2}O$ is the correct representation of reaction occurring when HCl is heated with $Mn{O}_2$