The \mathrm{Mn}^{3+} ion is unstable in solution and undergoes disproportionation to give \mathrm{Mn}^{2+}, \mathrm{MnO}_{2}, and \mathrm{H}^{+}ion. Write a balanced ionic equation for the reaction.
The \mathrm{Mn}^{3+} ion is unstable in solution and undergoes disproportionation to give \mathrm{Mn}^{2+}, \mathrm{MnO}_{2}, and \mathrm{H}^{+}ion. Write a balanced ionic equation for the reaction.

Solution:

The response is as given beneath:

\mathrm{Mn}_{(a q)}^{3+} \rightarrow \mathrm{Mn}_{(a q)}^{2+}+\mathrm{MnO}_{2(s)}+\mathrm{H}_{(a q)}^{+}

The oxidation half response:

\mathrm{Mn}_{(a q)}^{3+} \rightarrow \mathrm{MnO}_{2}(\mathrm{~s})

Add 1 electron to adjust the oxidation no. :

M n_{(a q)}^{3+} \rightarrow \operatorname{MnO}_{2(s)}+e^{-}

Add 4 H^{+}ions to surplus the charge:

M n_{(a q)}^{3+} \rightarrow \operatorname{MnO}_{2(s)}+e^{-}+4 H_{(a q)}^{+}

Add 2 \mathrm{H}_{2} \mathrm{O} to surplus \mathrm{O} molecules and \mathrm{H}^{+}ions:

\mathrm{Mn}_{(a q)}^{3+}+2 \mathrm{H}_{2} \mathrm{O}_{(t)} \rightarrow \mathrm{MnO}_{2(s)}+e^{-}+4 H_{(a q)}^{+} - - (1)

The decrease half response:

M n_{(a q)}^{3+} \rightarrow M n_{(a q)}^{2+}

Add 1 electron to adjust the oxidation no. :

\operatorname{Mn}_{(a q)}^{3+}+e^{-} \rightarrow M n_{(a q)}^{2+} - (2)

Add condition ( 1 ) and (2) to get the reasonable substance condition:

2 \mathrm{Mn}_{(a q)}^{3+}+2 \mathrm{H}_{2} \mathrm{O}_{(t)} \rightarrow \mathrm{MnO}_{2(s)}+2 \mathrm{Mn}_{(a q)}^{2+}+4 \mathrm{H}_{(a q)}^{+}