10 moli H2SO4
g ,moli oxigen
MH2SO4=2+32 +64=98--------> 98g/moli
-se afla masa de H2SO4 [m ]
n=m : M [ n=nr.de moli ; m=masa subst. ; M=masa molara ]
m=n . M
m=10moli .98g/moli=980g H2SO4
98g H2SO4------------------64g O
980 g H2SO4-----------------x
x=980. 64 : 98=640 g O
n=m : M
n=640g : 32 g/moli=20 moli oxigen
