C3H8 (g) + 3 O2 (g) → 4 H2 (g) + 3 CO2 (g)
This is an oxidation-reduction (redox) reaction:
3 C-8/3 - 20 e- → 3 CIV (oxidation)
8 HI + 8 e- → 8 H0 (reduction)
6 O0 + 12 e- → 6 O-II (reduction)
C3H8 is a reducing agent, C3H8 is an oxidizing agent, O2 is an oxidizing agent.