A,H2=2g/mol-----------------------------------> n,mol=m/A; n=2g/2g/mol=1mol H2
1mol 1mol 2mol
H2 + Cl2---> 2HCl
1mol 2mol----> n= 2molHCl
1mol contine 6,023x10²³molecule
2mol.....................2x6,023x10²³molecule=......................calculeaza !!!!