FeCln +n AgNO3----------->n AgCl
↓
+Fe(NO3)n
-------- ---------
MFeCln= (56+35,5n ) g/mol
MAgCl=143,5 g/mol
56+35,5n) g FeCln.....................n*143,5 g AgCl
100 g FeCln.................................2,65g =====>n=........
o ecuatie cu necunoscuta in n (cu n am notat valenta Fe)