Question

Fe2+ + MnO-4 --> Fe3+ + Mn2+

Fe2+ = +2
Mn = +7
O-4 = 4(-2) = -8
Fe3+ = 3+
Mn2+ = 2+
ok so next I gave 8H to MnO-4 and 4 H20 to Mn2+
Next I starting adding my electrons. 1e- to Fe3+. I understand that.
This is where Im lost according to my book I give 5e- to the reactant side.
Can you explain why it gets 5e-

Answer 1

The simple answer is that Mn changed frm +7 to +2 so it must have gained 5e.
MnO4^- + 8H^+ + 5e ==> Mn^2+ + 4H2O