The Mn3+ ion is unstable in solution and undergoes disproportionation to give Mn2+, MnO2, and H+ ion. Write a balanced ionic equation for the reaction.
The given reaction can be represented as:
Mn3+(aq) → Mn2+(aq) + MnO2(s) + H+(aq)
The oxidation half equation is:
M+3 n3+(aq) → M+4 nO2(s)
The oxidation number is balanced by adding one electron as:
Mn3+(aq) → M nO2(s) + e-
The charge is balanced by adding 4H+ ions as:
Mn3+(aq) → M nO2(s) + 4H+(aq) + e-
The O atoms and H+ ions are balanced by adding 2H2O molecules as:
Mn3+(aq) + 2H2O(l) → MnO2(s) + 4H+(aq) + e- ..... (i)
The reduction half equation is:
Mn3+(aq) → Mn2+(aq)
The oxidation number is balanced by adding one electron as:
Mn3+(aq) + e- → Mn2+(aq) ....... (ii)
The balanced chemical equation can be obtained by adding equation (i) and (ii) as:
2Mn3+(aq) + 2H2O(l) → MnO2(s) + 2Mn2+(aq) + 4H+(aq)
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(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
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(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
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