Write the half-rxns for the following unbalanced equation: ?

Question

MnO4^1-(aq)+Cl-(aq)--> Mn2+(aq) +Cl2(g) (in acidic solution)

I need the anode half-rxn and the cathode half-rxn

Answer 1

Break up the reaction into two half-reactions, one for Mn and one for Cl.

MnO41- ----->  Mn2+

2Cl-  ----> Cl2

Balance the main atoms - Mn and Cl

MnO41- ----->  Mn2+

2Cl-  ----> Cl2

Balance the oxygens by adding water

MnO41- ----->  Mn2+ + 4H2O

2Cl-  ----> Cl2

Balance the hydrogens by adding H+

MnO41- +  8H+  ----->  Mn2+ + 4H2O

2Cl-  ----> Cl2

Balance the charge by adding electrons to the more positive sides of each half-reaction.

MnO41- +  8H+ + 5e-  ----->  Mn2+ + 4H2O (cathode - reduction)

2Cl-  ----> Cl2 + 2e-  (anode - oxidation)

For the overall reaction, take the first reaction times 2 and the second times 5 to equalize the number of electrons gained and lost. Then add the two half-reactions together.