M,Mg=24g/mol; M,O2=32g/mol
n(niu)= m/M---> n,Mg= 96g/24g/mol= 4mol
2mol..........1mol..........2mol
in moli 2 Mg + O2----> 2MgO
4mol x=2mol.........y= 4mol
in grame
m=nxM
m,O2= 2molx32g/mol=..........................calculeaza !!!!
m,MgO= 4mol(24gMg+16gO)/mol=...................................calculeaza !!!