2 moli Cl2
n=m :M n= nr. de moli ; m=masa subst. ; M=masa molara
m=n . M
m=2moli . 71 g/moli=142 g clor [MCl2=2.35,5=71----> 1mol=71g[71g/moli]
3 kmoli NH3
MNH3=14 +3=17------> 1mol=17g [17g/moli ] ; [ 3kmoli=3000 moli ]
m=n.M
m=3000 moli .17g/moli=51000g NH3