Write the reaction equation: P – P2O5 – x – Ca3 (PO4) 2 – Ca (H2PO4) 2

1) 2P2 + 5O2 = 2P2O5 (when phosphorus interacts with oxygen, phosphorus oxide is formed);

2) P2O5 + 3H2O = 2H3PO4 (when phosphorus oxide interacts with water, orthophosphoric acid is formed);

3) 2H3PO4 + 3CaO = Ca3 (PO4) 2 + 3H2O (when phosphoric acid interacts with calcium oxide, calcium orthophosphate and water are formed);

4) Ca3 (PO4) 2 + 4H3PO4 = 3Ca (H2PO4) 2 (when calcium orthophosphate interacts with orthophosphoric acid, calcium dihydrogen phosphate is formed).