P40 + 2 NaOH + 4 H2O 2 NaH2PIIIO3 + 2 P-IIIH3

This is an oxidation-reduction (redox) reaction:

2 P0 + 6 e- 2 P-III (reduction)

2 P0 - 6 e- 2 PIII (oxidation)

Change the oxidation states