Răspuns:
5g Zn .......................................... 100% impura
masapura .................................... 97,5%
masa pura =97,5×5/100=4.875g Zn pur
4,875-3,25=1,625g Zn ce a reactionat cu solutia de CuSO4
65g.........160g
Zn + CuSO4 → ZnSO4 + Cu
1,625g......xg
MZn=65g/mol
MCuSO4=64+32+4×16=160g/mol
x=1,625×160/65=4g CuSO4
md=4g CuSO4
C=md×100/ms
C=4×100/250=1,6%
Explicație: