2 SCN- + 7 I2 + 8 H2O → 2 SO42- + 14 (I)- + 16 H+ + (CN)2
This is an oxidation-reduction (redox) reaction:
2 S-II - 16 e- → 2 SVI (oxidation)
2 CIV + 4 e- → 2 CII (reduction)
14 I0 + 14 e- → 14 I-I (reduction)
SCN- is a reducing agent, SCN- is an oxidizing agent, I2 is an oxidizing agent.