K2Cr2O7O4 + 7 C2H5OH + 4 H2SO4 → 7 CH3CHO + Cr2(SO4)3 + K2SO4 + 11 H2O
This is an oxidation-reduction (redox) reaction:
7 C-II - 21 e- → 7 CI (oxidation)
7 C-II + 7 e- → 7 C-III (reduction)
2 CrX + 14 e- → 2 CrIII (reduction)
C2H5OH is a reducing agent, C2H5OH is an oxidizing agent, K2Cr2O7O4 is an oxidizing agent.