CH4 +2O2---> CO2+2H2O x a moli
C2H6 + 7/2O2--> 2CO2+3H2O x b moli
C3H8 + 5O2---> 3CO2 +4H2O x c moli
b/a= 2/1--> b=2a c/b=3/2---> c/2a=3/2---> c=3a
FAC BILANTUL DE MASA
ax16g +bx30g+cx44g= 416g
inlocuind b si c---> a= 2mol
niuO2= 4+14+30--> 48mol
V,O2= 48X22,4 L=1075,2 L
V aer= 100/20x V.O2= 5X1075,2 L=....................CALCULEAZA