• if acidic, use H+ to balance hydrogen
    8 H+ + MnO4- → Mn2+ + 4 H2O                  Fe2+ → Fe3+
  • balance charge with electrons
    5 e- + 8 H+ + MnO4- → Mn2+ + 4 H2O        Fe2+ → Fe3+ + e-
  • equalize electrons (LCM)
    5 e- + 8 H+ + MnO4- → Mn2+ + 4 H2O        5(Fe2+ → Fe3+ + e-)
  • recombine half-reactions, simplifying where possible
    8 H+ + MnO4- + 5 Fe2+ → Mn2+ + 4 H2O + 5 Fe3+
It looks impossible the first few times. It's not.

Your drop titration reveals something important about the solution chemistry we've done so far and the coefficients in the balanced equation. Stay tuned for Unit 3.