Question

A green solution of potassium manganate (VI) turns purple and a brown solid is precipitated, when $C{O}_2$ gas is bubbled through the solution.

The above change is observed when $C{O}_2$ gas is passed into an aqueous solution of the given ion. The function of $C{O}_2$ is:

• A. It makes the solution acidic due to the formation of $H_{2}C{O}_3$
• B. It makes the solution basic due to the formation of $O_3^{2-}$
• C. It is simply the medium of the reaction
• D. None of the above is correct

Answer 1

The correct option is A It makes the solution acidic due to the formation of $H_{2}C{O}_3$

It makes the solution acidic due to the formation of $H_{2}C{O}_3$.

$C{O}_2+H_{2}O\to \underset{carbonicacid}{H_{2}C{O}_3}$

$3K_{2}Mn{O}_4+2C{O}_2\to \underset{purple}{2KMn{O}_4}+\underset{\left(brownsolid\right)}{Mn{O}_2}+2K_{2}C{O}_3$