(Mn)2+ + 2 BiO3 + 4 H+ → MnO4 + 2 (Bi)3+ + 2 H2O
This is an oxidation-reduction (redox) reaction:
MnII - 6 e- → MnVIII (oxidation)
2 BiVI + 6 e- → 2 BiIII (reduction)
Mn2+ is a reducing agent, BiO3 is an oxidizing agent.
Warning: Unknown compound 'MnO4'