p= 90%
p/100=m,pur/m,impur; 90/100= m,pur/80---> m,pur=72g
1mol .....2mol
Fe + 2HCl--> FeCl2 +H2
56g........2x36,5g
72g..........m= 93,8gHCl---> este masa dizolvata ,md, in solutia data
c/100= md/ms; 36,5/100= 93,8/ms----------------> ms= calculeaza !!!!!