A,P= 31g/mol---> niu= m/A= 2000g/31g/mol= 54,5molP
din ecuatia reactiei deduc moli P2O5, apoi masa
4mol........................2mol
4P + 5O2---> 2P2O5
54,5mol.........................niu=32,26mol P2O5\
m= niuxM= 32,26molx142g/mol=........................calculeaza !!!!!
