16 H3O+ + 3 C2-IIH5OH + 2 Cr2VIO72- 3 C20H4O2 + 4 (CrIII)3+ + 27 H2O

This is an oxidation-reduction (redox) reaction:

6 C-II - 12 e- 6 C0 (oxidation)

4 CrVI + 12 e- 4 CrIII (reduction)

Change the oxidation states