5 P-IIIH3 + 8 LiMnVIIO4 + 12 H2SO4 8 MnIISO4 + 5 H3PVO4 + 4 Li2SO4 + 12 H2O

This is an oxidation-reduction (redox) reaction:

5 P-III - 40 e- 5 PV (oxidation)

8 MnVII + 40 e- 8 MnII (reduction)

PH3 is a reducing agent, LiMnO4 is an oxidizing agent.