5 C3H6 (g) + 18 KMnO4 (aq) + 27 H2SO4 (aq) → 18 MnSO4 (aq) + 9 K2SO4 (aq) + 15 CO2 (g) + 42 H2O (l)
This is an oxidation-reduction (redox) reaction:
18 MnVII + 90 e- → 18 MnII (reduction)
15 C-II - 90 e- → 15 CIV (oxidation)
KMnO4 is an oxidizing agent, C3H6 is a reducing agent.