write equation for reaction between phosphorus and oxygen and then between water.
The reaction between phosphorus and oxygen leads to the formation of formation of phosphorus pentaoxide, which exists as a diamer of P4O10. This reaction is written as follows
P4 + 5O2 → P4O10
The reaction between P4O10 and water is given as follows
P4O10 + 6H2O → 4H3PO4