MCl2=2ACl=2*35,5=71g/mol
MH2=2AH=2*1=2g/mol
MHCl=AH+ACl=1+35,5=36,5g/mol
n=m/M=71/71=1 mol Cl2
H2 + Cl2 => 2HCl
1 mol Cl2...................2*36,5g HCl
1 mol Cl2.....................x=73g HCl
1 mol Cl2......................2 moli HCl
1 mol Cl2.....................x= 2 moli HCl