In: Chemistry
Balance the reaction in acidic solution.
MnO4- + Al ----> Mn2+ + Al3+
Given unbalanced reaction is
MnO4- + Al
Mn2+ + Al3+
By identufying redox couple , we wil write half reactions
Oxidation : Al
Al3+
Reduction : MnO4-
Mn2+
Now , balancing the oxygen atom , we will have
Oxidation : Al
Al3+
Reduction : MnO4-
Mn2+ +4H2O
Now balancing the hydrogen atom
Oxidation : Al
Al3+
Reduction : MnO4- +8H+
Mn2+ +4H2O
Now balancing the charge
Oxidation : Al
Al3+ + 3e
Reduction : MnO4- +8H+ + 5e
Mn2+ +4H2O
Now making electron gain equal to electron lost
Oxidation : 5Al 5
Al3+ + 15e
Reduction : 3MnO4- + 24H+ + 15e
3Mn2+ + 12H2O
Now adding half reactions together , So
5Al + 3 MnO4- + 24H+ + 15e
5
Al3+ + 15e + 3Mn2+ + 12H2O
We get final balanced reaction in acidic solution
5Al + 3MnO4-
+24H+
5Al3+ + 3Mn2+ + 12H2O