3 Na2(COO)2 + 2 Na2CrO4 + 8 H2SO4 → 5 Na2SO4 + Cr2(SO4)3 + 6 CO2 + 8 H2O
This is an acid-base reaction (neutralization): Na2CrO4 is a base, H2SO4 is an acid.
This is an oxidation-reduction (redox) reaction:
6 CIII - 6 e- → 6 CIV (oxidation)
2 CrVI + 6 e- → 2 CrIII (reduction)
Na2(COO)2 is a reducing agent, Na2CrO4 is an oxidizing agent.