-ecuatia reactiei:
P4 + 5O2---> 2P2O5 .....este pentaoxidul de fosfor( am simplificat cu 2 in P4O10)
4x31g..P.........................2(2x31gP+5x16gO) sau
124gP...........................2x142g oxid
124g.............................................m= calculeaza !
142gP205......................80gO
80g............................................m=calculeaza !