2 C3-8/3H8 + 7 O20 6 CIIO-II + 8 H2O-II

This is an oxidation-reduction (redox) reaction:

6 C-8/3 - 28 e- 6 CII (oxidation)

14 O0 + 28 e- 14 O-II (reduction)

C3H8 is a reducing agent, O2 is an oxidizing agent.