6 NaI (aq) + 2 Na2CrO4 (aq) + 5 H2SO4 (aq) → 5 Na2SO4 (aq) + 3 I2 (s) + Cr2O3 (s) + 5 H2O (l)
This is an acid-base reaction (neutralization): Na2CrO4 is a base, H2SO4 is an acid.
This is an oxidation-reduction (redox) reaction:
6 I-I - 6 e- → 6 I0 (oxidation)
2 CrVI + 6 e- → 2 CrIII (reduction)
NaI is a reducing agent, Na2CrO4 is an oxidizing agent.
This is a precipitation reaction: I2 andCr2O3 is the formed precipitate.